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Motherboard Design Process

CmdrTaco posted more than 10 years ago | from the get-all-up-in-that dept.

Hardware 87

MBRFan writes "MBReview has posted the latest revision of their 'Motherboards - The Designing Process' article. This article covers the design process for modern motherboards, and also goes over some of the most common components that can be found. Definite read for information lovers, though beware, it'll take a while to read!"

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I HATE ALL OF YOU! (-1, Troll)

Anonymous Coward | more than 10 years ago | (#10264630)

Go to hell.

Love Always,
News For Turds

Re:I HATE ALL OF YOU! (-1, Offtopic)

bob_avernus (799481) | more than 10 years ago | (#10264648)

such hostility...

Maybe someday they could get it right. (0, Insightful)

Anonymous Coward | more than 10 years ago | (#10264638)

Seems to be something which I dream of.

Wrong placement of capacitors and stupid placement of ports.

Re:Maybe someday they could get it right. (-1, Offtopic)

Anonymous Coward | more than 10 years ago | (#10264649)

So you are saying that you have problems with capacity and you don't like where her ports are? Very interesting.

Re:Maybe someday they could get it right. (3, Informative)

Timesprout (579035) | more than 10 years ago | (#10264876)

How does crap like this get modded insightful? There are many factors involved in a production process such as motherboards. In many cases trade offs will have to be made between engineering, manufacturing and cost. If the AC who feels maufacturers are not doing the job properly may I suggest he/she/it puts forward a better design than can be mass produced and afforded by the general population

nigger jokes (-1, Troll)

Anonymous Coward | more than 10 years ago | (#10264640)

so, does anyone have any good nigger jokes?

Re:nigger jokes (-1, Offtopic)

Inda (580031) | more than 10 years ago | (#10264911)

A black man walks into a bar with a parrot on his shoulder.

The barman says "Where did you get that?"

"Africa" says the parrot.

Doesn't make sense to me... (-1, Flamebait)

Omicron32 (646469) | more than 10 years ago | (#10264641)

As mentioned in the above paragraph, the Prepreg actually helps to dictate the static impedance of the trace on the signaling layer/s. The impedance is determined by a combination of factors such as the Er, or dielectric constant, of the Prepreg, and the height of the trace above the copper layer, which is itself determined by the thickness of the Prepreg that is utilized.

What the fuck?

Re:Doesn't make sense to me... (2, Insightful)

Neuroelectronic (643221) | more than 10 years ago | (#10264870)

That article kicks ass. I feel smarter already. I never knew EMI and line noise was such a problem for MoBo designers.. What a bitch that must be

Doesn't make sense to most people (3, Informative)

Anonymous Coward | more than 10 years ago | (#10264880)

IANAMBD, but...

"trace" == Metal tracks carrying the current

"Prepreg" == insulating "silk" layer separating the metal tracks running above and below.

"static impedance" == "guess" they mean parasitic capacitances formed between the tracks crossing over each other, separated by the "Prepeg".

"Er, or dielectric constant" == See physics book for parallel plate capacitor, the 'E' is the "greek epsilon"

"height of the trace" == the plate separation ... I.e the thickness of the "Prepeg"

.

The guy who wrote this article has a glittering career in the Patent business.

Re:Doesn't make sense to most people (0)

Anonymous Coward | more than 10 years ago | (#10265309)

"Prepreg" == insulating "silk" layer separating the metal tracks running above and below.

Not really, core and pre-preg materials are woven glass fiber in epoxy, also known as laminate. PCBs are built much like fiberglass boats, you get the fiberglass cloth and soak it in epoxy. The difference is that core is thicker and is just fiberglass, pre-preg is pre-impregnated with epoxy.
You stack those materials up, and put them in a heated press, you get your PCB.

The 'silk' layer is what is used to get all the (usually) white lettering on the PCB, against the (usually) green soldermask that is painted on the (usually) off-gray raw PCB material. It's called silk from silkscreen, the same process used for t-shirts.
Soldermask is what keeps solder on the pads of the chips instead of flowing all over the place and out of control.

Re:Doesn't make sense to most people (0)

Anonymous Coward | more than 10 years ago | (#10265795)

Imagine a signal going from 0 to 1. The voltage changes instantly, and some current flows. The amount of current is determined by the amount of inductance and capacitance per unit length of trace. But the speed of light is finite so the voltage step trundles along the trace charging up capcitors through inductance. After a while it gets to the end and the current has nowhere to go. So the laws of physics balance this out by sending a compensating voltage step back up the trace. It so happens you can stick a resistor at the end of the trace to give the curent someplace to go. Too high, the compensating step goes positive, too low it goes negative. Get it just right, all the current goes down the resistor to make a voltag e equal to the incident step, nothing bounces back, perfect signal. The value of the resistor is the characteristic impedance of the trace.

Re:Doesn't make sense to most people (0)

Anonymous Coward | more than 10 years ago | (#10269613)

"The voltage changes instantly"

Can't happen. Means infinite current. Sorry, try again.

Re:Doesn't make sense to most people (0)

Anonymous Coward | more than 10 years ago | (#10270650)

OK, a nitpick. Can you do better or are you just here to boost your ego at my expense? (Hint: I've got an electronic engineering degree, not an english language degree - and yes, I can design high speed circuits that work)

I wish I'd have read this earlier. :\ (1)

drunkennewfiemidget (712572) | more than 10 years ago | (#10264654)

Before I threw out my P2B-DS motherboard when it stopped working. I might have been able to do something about it. :\

Re:I wish I'd have read this earlier. :\ (0)

Anonymous Coward | more than 10 years ago | (#10275638)

You poor bastard. I have a P2B-D board (bought late 2000), and the only thing wrong with it is maybe a dead ram slot and a tempermental IDE controller. Good boards, I was really dissapointed to see Dual processing capability drop off from intel's standard features.

then i bought a mac. do i need say more?

It would have been interesting (5, Insightful)

antifoidulus (807088) | more than 10 years ago | (#10264667)

if they also gave a little insight into what goes into the manufacturing process as well. After all, you can design the best board there is, but if you have trouble making it in large quantities, it's not going to be successful. Cost and ease of manufacture should be factors in any engineering decision.

Re:It would have been interesting (3, Informative)

bsd4me (759597) | more than 10 years ago | (#10264782)

PC motheboards aren't terribly complicated as far as PWBs go. The don't really have a lot of components, and they don't have a lot of layers.

What is interesting about them, but I don't think it really complicates the manufacturing proces, is the effort that goes into reducing the number of layers (number of layers is directly related to cost). This compilcates both routing and signal integrity.

Re:It would have been interesting (2, Insightful)

Jeff DeMaagd (2015) | more than 10 years ago | (#10265215)

The don't really have a lot of components, and they don't have a lot of layers.

Compared to what? I understand some motherboards are pretty simple looking, but the ones that tend to be in my systems can get pretty complicated.

Re:It would have been interesting (1)

bsd4me (759597) | more than 10 years ago | (#10265749)

Take a look at some embedded electronics (such as cPCI boards) if you get a chance. A lot of these will literally use all available PWB real-estate, front and back) for components and also sometimes have to resort to daughterboards for more space (especially for memory).

Sorry to disagree (2, Insightful)

EightBits (61345) | more than 10 years ago | (#10265509)

PC motherboards typically have 4 - 6 layers. That's pretty complicated. Think about routing all of the signal lines of the PCI (64-bit) bus and memory bus. If you have AGP nad PCI-X, add those in ther too. Think of all the signals going from your IDE ports and SCSI ports (if you have them) to your chipset. If you have an opteron, you have in the neighborhood of 940 pins. They all get connected. That's a lot of nets and a lot of routing!

And, it's a good thing to reduce board layers to a certain point because adding layers gets expensive! While it does complicate the process, the process of routing the board is a one time process and thus a one time cost. Once the board is routed and tested, it's off to manufacturing where the cost of extra layers is recurring. It does complicate the manufacturing process in that now you have to glue together more layers after routing them. This is why more layers get so expensive. Those layers have to line up. With nets getting as small as they do, there is almost no room for error in lining these layers up. Very difficult. The more layers you add, the more likely you are to have layers aligned improperly. Someone has to eat the cost of those boards that cannot be sold and it wont be the manufacturer.

Re:Sorry to disagree (1)

bsd4me (759597) | more than 10 years ago | (#10265662)

PC motherboards typically have 4 - 6 layers. That's pretty complicated.

I guess I should have given a point of reference. I have worked on designs requiring 12-16 layers, even after conceding to use blind and buried vias and running the router for very long time (ie, days). That is pretty complicated.

Re:Sorry to disagree (0)

Anonymous Coward | more than 10 years ago | (#10269143)

Which autorouter did you use?

Sorry to disagree-Serial cereal. (0)

Anonymous Coward | more than 10 years ago | (#10266505)

"PC motherboards typically have 4 - 6 layers. That's pretty complicated. Think about routing all of the signal lines of the PCI (64-bit) bus and memory bus. If you have AGP nad PCI-X, add those in ther too. Think of all the signals going from your IDE ports and SCSI ports (if you have them) to your chipset. If you have an opteron, you have in the neighborhood of 940 pins. They all get connected. That's a lot of nets and a lot of routing!"

That's why you're going to see more and more of a serial design. PCI-X and SATA are more serial than parallel. With moores law and improved manufacturing technology. Having the signals come out in a serial fashion is easier. And it makes board manufacturing, and design easier.

Re:Sorry to disagree-Serial cereal. (1)

wolrahnaes (632574) | more than 10 years ago | (#10273549)

PCI-X and SATA are more serial than parallel.

*nitpick mode on*

PCI-X is heavily parallel. It's not much more than a faster clocked variant of good old 64-bit PCI.

PCI Express (PCIe) is the serial one. It uses multiple channels which can be bonded to make one large channel (as is used for PCIe x16 video hardware, 16 seperate PCIe channels in one slot).

Sweet (1)

Mr.Senator (813079) | more than 10 years ago | (#10264674)

w00t! Once I get $8mil and armed with this knowledge I can finally form my very own itty-bitty wittle motherboard...

... maybe I'll just check CompUSA

Not bad, but (5, Informative)

jimmyswimmy (749153) | more than 10 years ago | (#10264694)

I used to design motherboard power system components, and the author spends a good bit of time talking about that. That is actually the most complicated part of the board design, as it is not at all automated. Most component vendors try to sell a complete solution to the motherboard vendor, easing their job somewhat while helping the sales of the component vendor.

One particularly interesting item of note: all those capacitors the author describes are absolutely crucial, and together form one of the largest cost items on the board. The system is tested using a processor-vendor-supplied "load tool" which simulates the worst case load transients one can ever expect to see. Most of that testing is done by the power system component vendor and then provided as a block to the motherboard vendor. Most motherboard vendors have no idea what they are doing there.

In fact, a lot of the foreign manufacturers (no names) cost-reduce their designs by simply pulling out caps until the system blue screens. Then they put the last one back in and sell it. Intel is the only manufacturer I am aware of that actually sells the worst-case performing design.

Note that I am only aware of products related to Intel-type motherboards. I never worked on the othe stuff.

Re:Not bad, but (3, Interesting)

GigsVT (208848) | more than 10 years ago | (#10264761)

I guess the question is, will we ever be able to go back to the days when the actual computer power supply did the supplying of power, rather than having a second power supply on the motherboard?

Or are the extremely low voltages and high currents involved with modern CPUs going to always tie us to the motherboard, due to the necessary wires gauges to carry that sort of power at low voltage?

Re:Not bad, but (1)

Zzootnik (179922) | more than 10 years ago | (#10264943)

Nah- That shouldn't be a problem as soon as the light-based processors start...be-ing. (Cause they don't exist yet!)

I imagine there will be a power supply that provides juice to a single light source and whatever switches are needed. Fiber will carry the light pulse signals instead of traces on a motherboard. You probably wont need that big ol heatsink on the northbridge chipset... And you won't even need to add any of those freakish cathode lamps and other lighting gizmos to your windowed case... Anyone know if fiberoptic cable comes in cool colors?

Re:Not bad, but (1)

marcus (1916) | more than 10 years ago | (#10264982)

The low voltages and high currents are exactly the reason for the on-board power supplies. Distribution and regulation are very difficult if not impossible at such low voltages where the needed current is high and resistance/impedance varies even slightly from trace to trace.

This is also the reason for so called high-tension lines from power plants. High voltage at lower current is less sensitive to distribution path variations and has less loss over a given impedance/distance than does a lower voltage/higher current scheme.

If you think about it, hierarchical power distribution schemes have existed since AC. They are simply more efficient than monolithic schemes.

Re:Not bad, but (1)

JCMay (158033) | more than 10 years ago | (#10265825)

The reason for high-voltage power distribution isn't load regulation as much as power loss. Wires are resistive and have losses that proportional to the square of the current (Pdiss= I^2 * R).

By distributing electric power at higher voltages, the same total power can be transmitted at a lower current (P= V*I), so that lower line-resistance losses are incurred, increasing efficiency.

Re:Not bad, but (3, Insightful)

Billy69 (805214) | more than 10 years ago | (#10265427)

Erm, what happens on the mobo is really just a case of regulation, not a separate 'power supply' as such.

And board-level power regulation goes back at least as far as the IBM XT (yup, I had one, they had 7805 5v regulators on them)

But to answer the question I think you are asking, which is why doesn't the PSU supply the processor voltages, you have to think about the number of different processor and interface voltages there have been over the last few years. Processors have gone from using 5v logic supplies down to what, 0.8v now, via dozens of different steps in between. So to supply the voltage direct from the PSU would require either a PSU tied to a specific motherboard which was tied to a specific small group of processors, or a PSU with about 30 different voltage outputs. Both of these options are a lot more complex and painful than just regulating the voltage on the motherboard.

Re:Not bad, but (1)

chenwah (161707) | more than 10 years ago | (#10273416)

No, the components on the board really do form part of the power supply.

Because of the way processors draw current - bursts of current when switching - the rate of change of current can be enormous, in the range of giga-amps per second. If high-speed digital circuits like motherboards did not have a heirachical power supply the inductance in the power supply network would completely eliminate the ability to deliver the AC current needed.

Motherboards will use a heirachy of power supply components starting at the PSU which supplys the base DC load (big caps, long thin leads with high inductance) and ending with capacitors right next to the processor to supply the fast instantaneous current necessary for switching.

So while people might think of the power supply as the big silver box in the corner of the case with the fans and the whirring and the whathaveyou, on a motherboard the power supply is a network including the PSU and the motherboard components. Sure there is voltage regulation, but power supply in a high speed multi-layer digital circuit is a lot more than that.

Of course I have never built something like this, but I took this subject last semester: http://www.unimelb.edu.au/HB/subjects/431-467.html [unimelb.edu.au]

- flip -

Re:Not bad, but (2, Informative)

jimmyswimmy (749153) | more than 10 years ago | (#10266632)

As another poster pointed out, until a complete shift in technology occurs, this will not happen. Power loss in a wire follows the law P=VI. The lower the CPU supply voltage, the higher the input current will be.

We continue to move to higher CPU switching frequencies and lower CPU voltages. Why? Well, higher frequency means higher clock speed, and greater processing power. Another way to increase processing power is to add complexity to the circuit, which means a larger chip. BUT, you can reduce the size of the chip by reducing the size of the features required to implement your changes. And that, my friend, means you need a lower voltage, or you will destroy those tiny, delicate features (breakdown the MOS gate oxide layer).

The relationship between power loss, switching frequency, and voltage, is straightforward:

P = C*V*f

You can't really work that out for a modern CPU but it is illustrative.

And with upwards of 100 A at less than 1.5V driving your CPU, motherboards will have an onboard VR (voltage regulator) for years to come. I used to test with an old ATX supply (before the ATX 2.0 spec added the tiny 2x2 12 V connector) and after pulling 12 A through the single wire supplying 12 V for fifteen minutes, the insulation became brittle and browned. You would need to more than double your existing wires just for DC... and don't get me started about all those capacitors again!

Re:Not bad, but (0)

Anonymous Coward | more than 10 years ago | (#10269219)

We have a 30kW DC motor at work which can give 100+ amps. The wires are about a centimeter in diameter. Needless to say, they would be a bit unwieldy inside a computer case. Their minimum bend radius is about half an ATX case .-)

Re:Not bad, but (1)

mnmn (145599) | more than 10 years ago | (#10265057)

We had a common issue at our company where the IBM motherboards would have their capacitors pop. i.e. the top plate would bulge, and the system would randomly freeze. IBM replaced something like 12 motherboards at our company, various models with the same issue. So I dont think the noname vendors are the only ones.

The few nonames (Athlon/Duron) motherboards that I do have at home work relatively fine, with the problem of badly implemented BIOS. Funny how almost all Pentium 1 machines still work and are pretty robust while the newer class machines crash out more and more frequently. And I checked the single unit price of those electrolytic capacitors are in cents. (I'd love to pay $10 more for stability).

I wonder if VRMs can be standardized so people would start using those the way they'd use cache modules on Pentium1 boards. That'd call for highed quality VRM modules.

Not IBM's fault (1)

Roadkills-R-Us (122219) | more than 10 years ago | (#10266322)

When did this occur? A couple of years ago, there were some bad caps on the market after an employee stole *part* of the dielectric formula when he left one cap company for another. The new company used his process/formula without knowing it was incomplete, an dthe result was bad caps on boards from quite a few vendors.

I don't recall whether the vendor was found culpable, or just the employee.

I know it was covered on slashdot...

Re:Not IBM's fault (1)

Enigma2175 (179646) | more than 10 years ago | (#10268092)

I don't recall whether the vendor was found culpable, or just the employee.

I know it was covered on slashdot...


Here [ieee.org] is an article about the problem on IEEE Spectrum. I have had to replace many motherboards because of this problem, all MSI or Epox.

Re:Not bad, but (1)

jimmyswimmy (749153) | more than 10 years ago | (#10266346)

Actually, the electrolytic capacitors used by most companies are definitely in cents, but they are in the thirty to fifty cent range typically. If you think about that, for the recent P4-type motherboards, you're looking at around 6-12 of these, if they do it right, and depending on a variety of factors. That's $18 minimum! And no vendor can advertise that their motherboard is "rock solid," because something is eventually gonna cause it to crash. So, looking at two boards on the shelf, would you really spend $20 more? Well, you can tell by looking at your existing motherboard. If it's an Intel, then I guess you do.

VRM's cost a fortune. You have to pay for an extra board (cheap, but...), the connector, and more of those expensive capacitors, usually. Even the cheap stuff adds up. VRM's are only appropriate where you have a multiprocessor system and you plan to start with one processor and build up later.

Re:Not bad, but (1)

LordMyren (15499) | more than 10 years ago | (#10266931)

you mean like the VRM's on the PPro & Xeon's?

Re:Not bad, but (1, Interesting)

Anonymous Coward | more than 10 years ago | (#10266606)

I always leave 3 or 4 no stuff capacitors (Bulk and HF)on the motherboards I work on (and I AM a power engineer). That way when I do buy one of these systems I can add the extra caps fairly easily and I'll get a system that I can actually trust.

I find that the industry is only now starting to appreciate how difficutly power supply design is.

-Coward cause I don't want my boss to hear (Empty Caps locations means harder buss routing because the vias go alllll the way through the MB)

Re:Not bad, but (1)

Brians256 (562930) | more than 10 years ago | (#10267962)

What kind of caps do you typically use? In other words, what specs do you find are most critical? Is it ESR of some amount or do you just go for bulk capacitance? Also, what about the inductors and MOSFETs? I find that many motherboards have inductors that get extremely hot. Heat = wasted energy and I've always wondered how easy it would be to upgrade some of the components on-board. Plus, that extra heat does no good for the neighboring CPU. I've got my computer down to one fan, and I could use a smaller fan if I could reduce the amount of heat being generated. Quiet, reliable, efficient and cool computers are good.

Re:Not bad, but (1)

addaon (41825) | more than 10 years ago | (#10268490)

I could use a smaller fan if I could reduce the amount of heat being generated. Quiet, reliable, efficient and cool computers are good.

Bigger fans are quieter, more reliable, more efficient, and cool better.

Re:Not bad, but (1)

Brians256 (562930) | more than 10 years ago | (#10269129)

True, which is why I'm using a 192mm fan. However, I think that most 192mm fans are fairly noisy even when PWMed or downvolted. They aren't built to be quiet. However, there are a number of 120mm fans that are built to be quiet. If I need less CFM for cooling, I could use one or two 120mm fans that are meant for quieter (and thus less CFM) operation.

Re:Not bad, but (0)

Anonymous Coward | more than 10 years ago | (#10269373)

Something you should be aware of concerning inductors is that if they are ferrites, their optimal temperature is usually 100 C. That's where they have the least losses. So the inductor will quickly heat up to 60 C or more, but once there is will actually have lower losses. (The difference can be a factor of two for some materials and frequencies.)

You don't actually want to design your inductors to run at 100 C though, since losses increase above that, which can lead to thermal runaway (mmmm, fried computer!).

Re:Not bad, but (1)

jimmyswimmy (749153) | more than 10 years ago | (#10275576)

In the design of a CPU motherboard power supply, I suppose my two biggest concerns were heat and transient response. In dealing with the heat issue, you have to select the "best" components to make the system work. In other words, the cheapest set that will work. That's not trivial at all. First you decide how many phases to work with, considering that the norm is about 25-30 A per phase maximum. Then you pick a frequency. The operating frequency of the multiphase converter determines the inductors you use, and those get HOT at high frequency, due to core loss effects. Then the MOSFETs, and you parallel however many as are necessary to keep the heat down while also keeping the cost down -- usually an empirical selection process (hours upon hours in the lab learning what works and what doesn't).

On the other side you're dealing with transient response. That is, the CPU is working hard, decoding your DVD's and playing MP3's and all that other sht. And then, suddenly, it's not doing much at all. The load goes from, say, 110 A to 10 A, or at least that's how the design might go. Now you have to select capacitors to deal with that. These capacitors are selected based on some specified parameters, such as raw, bulk capacitance and ESR, as well as some unspecified ones, such as ESL and whether or not you have any in the lab. And they are tested and tested to death. It's amazing how much component placement and orientation can matter.

In the field, you do not have the tools to test the resulting design, so it's not a great idea to dick around with the decoupling solution. But for fun, if you had a motherboard to mess around with, you could try replacing whatever existing bulks with the smallest Sanyo OS-CON's you can find, or some of those sweet Fujitsu yellow caps, I never found a part number. If the total C is at least the same as what you had, it "might" work.

As far as MOSFETs go, to replace them you're mostly worried about heat. For the high side switches, you worry about gate charge Qg and thetaJA, the lower the better. For the low side switches, RDSON and thetaJA, the lower the better. The high side switches aren't on very much (only 1.5/12 of the time) and depending on the switching speed they will generate a lot of heat. So we want good switching capability out of them. The lowside switches are on 10.5/12 of the time so we want them to conduct well, with low resistance.

But if you replace the MOSFETs, and you happen to find low side switches with too high gate charge, the existing drivers may be unable to deal with them, and so you are screwed. Drivers can be tough, depending on whether or not they are standard. There is a fairly standard SO-8 format for driver pinouts that is ignored as often as it is accepted.

In short, there's not a lot you can do. Replacing inductors is too hard to do right, and same with the power design. Best bet, go with the Intel design (and no, I don't and didn't work for them, and I don't own stock in them, I just understand their methodology). If not, then buy the motherboard with the most phases (most big inductors around the CPU). That means the lowest current per phase and, if well designed, the best future CPU upgrading capability.

Re:Not bad, but (0)

Anonymous Coward | more than 10 years ago | (#10267740)

Intel is the only manufacturer I am aware of that actually sells the worst-case performing design.

Which would be nice if I could actually get my hands on an Intel motherboard. Here's a conversation I had once while shopping for a new computer:

Me: "Do you have Intel motherboards?"
Salesperson: (thinks, then answers)"Um, yeah, YEAH! we have Intel motherboards, of course we do!"
Translation: "We use crappy no name motherboards, but with Intel CPUs on them, which means I have plausible deniabily when this guy comes back and says I lied to him."
Me: (thinking) Umm, guy, that delay gave you away. Hell, I could see the hamster running in the wheel in your head when you did that. Take a lying seminar for God's sake. "Thats good to know. Good bye." See you later. Good riddance. Hasta la vista baby!

I can get ASUS motherboards around here (Toronto, Canada) which I like, but I've never even seen an Intel motherboard.

Re:Not bad, but (1)

cowbutt (21077) | more than 10 years ago | (#10268254)

Intel-branded boards are dead easy to find in the UK (though generally only mail order - fairs and mom n' pop shops frequently only sell cheap junk, though this has changed over the last few years and you can find Abit, MSI, Asus and Gigabyte quite easily), so I'm surprised you're finding them difficult to find in North America.

Have you tried using price comparison sites together with the Intel model numbers? (e.g. D865PERLX [pricenetwork.ca] ). If you need other model numbers, try checking dabs.com [dabs.com] or Intel's site first.

Personally, I'm pretty happy with Intel-based Asus and Gigabyte as they generally have more features for the same price as Intel's boards and have proven to be compatible and reliable for me. On the other hand, I can't help but notice that the quality vendors seem to use Intel-on-Intel boards in their top-of-the-line server hardware.

--

I've heard stories... (1, Informative)

Silverlancer (786390) | more than 10 years ago | (#10264706)

I've heard stories of crappy motherboards blowing capacitors. Which is why its always better to get the 150 dollar one than the 30 dollar one. Because the 30 dollar one is effectively made out of scrap metal...

Re:I've heard stories... (1, Informative)

Anonymous Coward | more than 10 years ago | (#10265131)

Nonsense! The capacitor issue you are talking about was due to defective manufacture of the capacitors. I see the effects to this day.

The thing is, capacitor failures were not limited to "cheap" motherborads! Although the more expensive boards may have had more effort in terms of worst-case design or more parts added to increase timing/noise margins, in the end they all send it overseas to be manufactured and those guys go out and buy the cheapest parts they can find. For a while, those were the badly manufactured capacitors mentioned above.

I reiterate: I have seen these capacitor failures in motherboards from major players as well as all the cheaper motherboard manufacturers. Buying a $150 dollar motherboard rather than a $30 one does not necessarily guarantee reliability.

manufacturer (2, Insightful)

GMail Troll (811342) | more than 10 years ago | (#10264718)

The design process for motherboards in my experience seems to depend on the manufacturer. Some take a more sloppy approach where the first version is riddled with bugs - take a look at Via's KT133 and subsequent KT133a for example (in some ways reminiscent to me of Redhat's notorious .0 releases). In general I'm more in favour of a rigourous approach when designing hardware - bugs in software are easy to fix (download a patch), but with hardware you expect what you're buying to work.


All in all a motherboard is a complicated piece of electronics so it isnt surprising that bugs sometimes creep in. As with software I expect it is the quality of the engineers working on it that is the ultimate deciding factor in the quality of the final product.


gmail invite [google.com]

Motherboard design is true art (4, Interesting)

Alwin Henseler (640539) | more than 10 years ago | (#10264746)

I have always considered motherboards THE most complex, interesting, and difficult part of a computer to design, and design well.

Every single component on a motherboard can be a magnificient piece of work, but it deals only with a limited number of variables. A CPU or chipset component ultimately only deals with bus protocols and internal design. The same goes for other components like memory or harddrives.

But everything comes together through the motherboard, and that (in my eyes) makes it the hardest part of a system to design well, considering the number of variables. A truly well done MB design is really a piece of art.

Re:Motherboard design is true art (1)

iamatlas (597477) | more than 10 years ago | (#10266656)

A truly well done MB design is really a piece of art.

Yes, but while mobos may be art, a piece of art is no necesarily a good mobo- The throughput on a Van Gogh is pretty crappy. Although, I've hear that mobos based on Much's "The Scream" can really move sometimes.

Re:Motherboard design is true art (1)

WinterpegCanuck (731998) | more than 10 years ago | (#10267939)

I concure full heartedly. Back in the early days of my computer career, I came across a 486 motherboard from a small company, I think was called Chico or Chimano, but anyways that little board with a 66DX chip could just rock and outperform first generation pentiums. Even loading it down in 3.1, it was just a solid performer. It was just the right combination of motherboard and ATI Mach 32 Vesa graphics card that matched well.

Similarly, I later came across a board that I could overclock my Cyrix (Yes, I know, stop laughing) 133 to 150, increading the bus speed from 66 to 75 and thus making the whole system operate faster, not just the processor. Again, an ATI card, this time a Mach 64, and this system was by far the most stable system yet outperformed 200-233 class pentium. As much as I have always loved AMD, in this case using one in this system made noticable differences to stability and speed.

As much as I think that Mobo's are the heart of the artistry, it really does come to chance sometimes that you just have the matching hardware that works well together. Despite the standards, there are so many minute variables that it really is a crap shoot.

Yes, but.. (4, Funny)

m0RpHeus (122706) | more than 10 years ago | (#10264749)

Yes... but does your motherboard manufacturer follow best practices like Feng Shui? [bbspot.com]

Re:Yes, but.. (4, Funny)

vurg (639307) | more than 10 years ago | (#10264866)

I think mine does. My northbridge is aligned to the northern dragon constellation, and my southbridge flows with the wind that which cannot be seen.

Re:Yes, but.. (1)

nbert (785663) | more than 10 years ago | (#10265818)

the last paragraph says it all:
Reviewers at several websites were unable to get the motherboard to power up in any configuration. Fengtek technical support said this would allow more time for meditation.

I wonder... (2, Funny)

genixia (220387) | more than 10 years ago | (#10264788)

Why do motherboard manufacturers make a big deal out of multi-layer PCB's?


LOL, I'd like to see them try and make a single-layer motherboard!

Re:I wonder... (2, Funny)

freqres (638820) | more than 10 years ago | (#10265054)

Nah, make a wire-wrap version of a modern day motherboard.

Re: One word: cost (1)

Alwin Henseler (640539) | more than 10 years ago | (#10265525)

Why do motherboard manufacturers make a big deal out of multi-layer PCB's?

Roughly speaking, more PCB layers makes it easier to do a complex design, but harder (read: more costly) to do the manufacturing.

The mobo market is very competitive, so shaving a single $ of the price of manufacturing a board, is profit/market advantage for a mobo maker. So the mobo maker will try to keep the number of PCB layers to the absolute minimum needed for the design. AFAIK, many mobo's use 4 layers.

True Revolutionary Design... (2, Funny)

Kozz (7764) | more than 10 years ago | (#10264856)

...comes with the wisdom of the Far-East, yessir!

What, you haven't heard of the Feng Shui Motherboard [bbspot.com] ?

"We didn't rely on reference boards or schematics from chip manufacturers. Those designs had too many straight lines and sharp corners, which are unnatural and direct poison arrows at our soul.

Re:True Revolutionary Design... (1)

Alsee (515537) | more than 10 years ago | (#10266140)

Ha! My motherboard is designed according to Time Cube [timecube.com] principals!

I would describe my motherboard, but Word is a Trojan Horse.

-

Motherboard manufacture (-1, Troll)

Anonymous Coward | more than 10 years ago | (#10264893)

1. take one mother
2. kill
3. hammer into required shape
4. rename cunt as AGP
5. profit!

Chinese contortionist (1)

NetNinja (469346) | more than 10 years ago | (#10265091)

Graphic cards hitting capacitors.
IDE and Floppy conectors on top of each other.
Fan connectors way at the bottom and not enough of them.

I have to be a Chinese contortionist to pulg things up once the motherboard is installed in a case.

Re:Chinese contortionist (0)

Anonymous Coward | more than 10 years ago | (#10267566)

>I have to be a Chinese contortionist to pulg things up once the motherboard is installed in a case.

That's why your job is outsourced to India or China where they can perform such impossible physical acts.

It is a bit disingenious really....... (1)

GuyFawkes (729054) | more than 10 years ago | (#10265355)


Because stage one of the design process is always going to be "what form factor we gonna go for?"

if it's ATX then 99% of the components can only go where they go, PCI slots have to go where they do, CPU has to go at the top cos pci slots extend to the bottom on cases, ide connects towards the "front" of the pc, psu cables near the top cos psu makers save money by shaving cable lengths, ram is an awkward shape so it can only go where it does, and all the i/o can also only go where it goes.

ok that leaves "some" slack for placing shit like fan headers, but bugger all for power devices like capacitors etc.

it's not like they can rats nest all the components and do auto routing AND auto placement to minimise pcb size or track length.

as another poster says, multi-layering as also inevitable unless you are going to use pc104 style stackable cards to get your extra routes on.

no, sadly too much of the design process is fixed by form factor, and too many mobo manufacturers are thus left with no real design decisions except..

"can we use six 20 cent capacitors instead of twelve 90 cent ones?"

and

"should we dye this one red? or black? or blue?"

end

Re:It is a bit disingenious really....... (0)

Anonymous Coward | more than 10 years ago | (#10268955)

That was the most unreadable piece of shit comment I've ever read. /. isn't known for being a bastion of grammatic expertise, but please, take an English class!! You are hurting us!

Re:It is a bit disingenious really....... (1)

VoidWraith (797276) | more than 10 years ago | (#10270788)

You must not read AC comments.

Yes but look at the cost to us... (1)

wg0350 (753504) | more than 10 years ago | (#10265441)

£12.95 will get you a (Pcchips KT266A SKT A DDR266 ATA133 AGP Sound LAN USB 2.0 ATX Retail Box) ebuyer [ebuyer.com]

This is not a recomendation of this particular motherboard, I simply took the item that was the top of the list. When you see something like this for this price it makes you wonder how they make their money. I know the quality is not great, it will probably die before too long, but thats not the point.

For that price how can someone make a motherboard that works even once?

FuCker (-1, Redundant)

Anonymous Coward | more than 10 years ago | (#10265860)

OpenBSD wanker Theo exactly what you've started work on base for FreeBSD happen. 'At least reasons why anyone of aal legitimate clearly become For it. I don't Bloc in order to

FYI, 1 mils = 2.54e-05 metre (2, Informative)

joostje (126457) | more than 10 years ago | (#10266008)

To save the other metric readers the trouble googling, 1 mils = 1/1000 inch = 2.54e-5 metre. conversion [simetric.co.uk]

Re:FYI, 1 mils = 2.54e-05 metre (1)

ezzzD55J (697465) | more than 10 years ago | (#10266177)

units(1) rocks for this sort of stuff. % units 510 units, 54 prefixes You have: 1 mil You want: 1 m * 2.54e-05 / 39370.079

Re:FYI, 1 mils = 2.54e-05 metre (1)

HokieJP (741860) | more than 10 years ago | (#10266484)

This is a pet peeve of mine. Why, oh why, can the electronics industry not say 'thousandths', or the ever-popular 'thou'?

Applying a metric prefix to an english unit violates people's expectations and creates confusion with millimeters.

What the author did tell you...... (0)

Anonymous Coward | more than 10 years ago | (#10266228)

was that Intel would sell any component vendor down the river AND shoot their grandma to save a nickle per board....

What a terribly written article (1)

Relic of the Future (118669) | more than 10 years ago | (#10266455)

I got as far as page 2 before leaving in disgust. I could follow it all easily enough (B.S. in ECE) and hit all the right technical points, but it was just so poorly written! Terribly sentence structure, terrible paragraph structure, several glaring spelling mistakes... I give it an A- for science&technology, but an F in English.

And if the author uses the word "basically" one more time, I'll throttle him.

Re:What a terribly written article (3, Funny)

Kehvarl (812337) | more than 10 years ago | (#10267129)

Basically what you're saying is...

diy potentials (1)

LordMyren (15499) | more than 10 years ago | (#10266504)

one of my friends graduated MIT when i was still a sophmore in HS twiddling with microcontrollers. i asked him what he could do with his CompE degree; he told me could build a motherboard. i was amazed, but then again i already knew i would be a CompE anyways. anecdote over.

with more and more cores becoming more and more embedded, sometimes i think there's a small possibility users might be able to again develop their own systems. alright, so i'll probably never build a motherboard for an intel desktop processor, but perhaps some hyper-evolved ARM or powerpc-derivative isnt entirely out of the question.

one of the classic challenges of motherboard design has always been where do you put all these signal paths. we have two solutions in the pipe aimed squarely at this: PCIe and FB-DIMM, both of which drop channel width dramatically.

i'm just a computer engineer (may '05 baby), they dont teach us much about the black art of high speed signalling, but somehow BGA gives me faith. it may mean you have to have your 6 layer board shipped to you, but that seems like an OK tradeoff for being able to design some amazingly high speed hardware without being a signal-foo master.

of course & as usual, the reality is probably highly departed from my little dream world. but its a nice thought, and i still think it might be possible. at least if i can afford some good PCB design software. that, i believe, will be the crux of the issue.

myren

Re:diy potentials (1)

Matt_Bennett (79107) | more than 10 years ago | (#10268775)

i'm just a computer engineer (may '05 baby), they dont teach us much about the black art of high speed signalling, but somehow BGA gives me faith. it may mean you have to have your 6 layer board shipped to you, but that seems like an OK tradeoff for being able to design some amazingly high speed hardware without being a signal-foo master.

The high speed busses atually mean you've got to be more of a high speed design master- True, there aren't as many traces, but you have to be much more careful about the traces you do put down. A very frustrating part of the high speed design process is that the signalling is so fast that even putting an additional pF or two of capacitance from a probe can completely change your signal.

For additional info on high speed signalling, check out Howard Johnson [signalintegrity.com] and his books. He is a high speed signalling master, and is very good at explaining it. If you ever get a chance to take one of his seminars, jump at it. Very definitely worth the time.

Re:diy potentials (1)

LordMyren (15499) | more than 10 years ago | (#10271057)

to be sure, matching your line becomes very exacting. but manufacturers usually have plenty of reference materials on how to lay good traces, what specs your shooting for.

getting paths down doesnt seem THAT hard. i want to work out each individual piece, lay my traces between two points and be done. everything short of 'my software will lay my traces for me'. thats not THAT sinfully bad. getting to spec doesnt look oh so difficult.

crosstalk, on the other hand, scares the crap out of me. you've got a board layed out that you KNOW has good impedences, know to be layed out right, know you have equal trace lenghts and its still not working. what then?

i know it'll end up an excuse to just use MORE pins, but right now halving the pin count seems really really nice. take this inquirer article on fb-dimm. article [theinquirer.net] . look at the difference! pci suffers a similar bus-going-everywhere effect which pcie reduces marginally.

with good solid connectors, good helpful specs, doing this stuff shouldnt be that hard. yes, its higher speed, but an idiot like me migh have a chance of making an uber-high-speed board if i use some liberal spacing.

i could be dead wrong.

Re:diy potentials (1)

Matt_Bennett (79107) | more than 10 years ago | (#10288706)

with good solid connectors, good helpful specs, doing this stuff shouldnt be that hard. yes, its higher speed, but an idiot like me migh have a chance of making an uber-high-speed board if i use some liberal spacing.

i could be dead wrong.


Ahh... The innocence of youth... Good to set your sights high, but, really, this stuff is hard. All of it. Spacing is only part of it- usually you can get enough spacing if it is 3x to 5x the height of the trace above the ground plane. But if you're talking about differential pairs (like you have to be with PCIE), then everything is different. Basically, once you get into the really fast edge rates, you've got to look at the wire as a transmission line. Remember "Smith Charts?" Most engineering students try to forget them, but hello, they're back!

I'm not just "talking a story" from what I've been reading off of the Internet- if you take a look at my URL, you can find out where I work (hint- rhymes with "hell"). We've just released our first PCIE systems, and they are by no means simple. PCIE is only a small part of the system. Heck, a huge portion of the time spent on a new motherboard is on the BIOS and working around chipset issues. Despite the popular opinion, the company I work for does design systems, working hand-in-hand with the silicon developers, from the first buggy silicon until they ship the first board.

What most people don't realize when they talk about getting a cheap new motherboard from some Asian company is that the systems were not (necessarily) initially brought up and the bugs found over there- most of them were brought up, debugged, and first brought to market by one of the big computer makers in the US. You win because those companies everyone disses spent their effort debugging them to get a slight head-start on the Asian manufacturers.

Re:diy potentials (0)

Anonymous Coward | more than 10 years ago | (#10269459)

but somehow BGA gives me faith

It shouldn't. It may have good performace, but it's bloody impossible for individuals and smaller co's to build prototypes with.

Re:diy potentials (1)

LordMyren (15499) | more than 10 years ago | (#10270879)

cant you get 6 layer boards for, what, like $60 a pop? if not, i know what i'm doing after i'm done with school; undercuting greedy ass punks.

sure you cant play with it like you can a breadboard. the tradeoff is you can actually get speed, something former packaging just didnt give you.

Re:diy potentials (0)

Anonymous Coward | more than 10 years ago | (#10272795)

Boy, are you going to be in for a shock when you hit the real world...

Re:diy potentials (1)

LordMyren (15499) | more than 10 years ago | (#10277678)

sure, but just what part do you think most ludicrous?

A good article on PCB design, bad on MB design (0)

Anonymous Coward | more than 10 years ago | (#10267274)

The article starts off interestingly, discussing
the nutty gritty details of designing the PCB.
But as it reaches the area of components, it
becomes a second grade electronics text book.
The author does not give any hint on why you need
so many different capacitors(shapes/sizes), and
why they are needed even if they are simply
paralleled. There is also no context of
noise due to simultaneous switching(except for
the cross talk etc.).Except for the first couple
of pages, the article becomes a definition for
electronic components, instead of how and why
they are used for motherboard design.
For those who does not know a cap/inductor, it
could be a good read, but not for me(being in
the field of VLSI design for the last 14+ years).
The article could be named as:
Basics of electronic components used in a mother
board design and PCB design.

Syntax Error! (0)

Anonymous Coward | more than 10 years ago | (#10267465)

...beware, it'll take a while to read!

Doesn't this kinda rule out the article as a Slashdot topic? I mean, what self respecting Slashdotter does a RTFA anyway?
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