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AMD Athlon64 4000+ Underclocking

CowboyNeal posted more than 9 years ago | from the slowing-things-down dept.

AMD 286

Bios_Hakr writes "PC Stats is running an article on their experiences underclocking an AMD 4000+ processor. Their goal was to try and reduce the voltage requirements and lower the heat output. They benchmark using 3dMark01, 3dMark05, as well as SuperPi. From the article: 'This got us thinking though; what about under-clocking? Most modern processors and motherboards can just as easily run under a rated speed as it can run over... but is there a point to this? Well possibly.'"

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Don't keep us in suspense (1)

Colin Smith (2679) | more than 9 years ago | (#12723214)

The point is.....?

If you want low power you can buy systems specifically designed to perform well on low power supply.

Re:Don't keep us in suspense (2, Insightful)

lukewarmfusion (726141) | more than 9 years ago | (#12723226)

The point is...

Suspense = more clickthroughs = more ad views = more revenue.

Then you can't crank it up when you need to. (1)

b00m3rang (682108) | more than 9 years ago | (#12723254)

n/t

Re:Don't keep us in suspense (3, Informative)

B'Trey (111263) | more than 9 years ago | (#12723264)

RTFA. From the article:

Case fans can generate some audible noise in an environment designed for quiet, and is this really acceptable? Professional studios can acoustically isolate computers, making this a moot point, but home audio enthusiasts don't have this luxury. The question is, how much heat and voltage can be dumped by underclocking a given processor (down) while still retaining acceptable processing performance?

The purpose of this article is to take a very fast, very hot modern processor (in this case an AMD Athlon 64 4000+) and underclock it with an eye to comparing performance to levels of heat and voltage at below stock speeds. The Athlon 64 is currently the fastest available desktop processor, so we reasoned that reducing its speed to the point where it could be operated silently with a passive cooling system should still leave us with a powerful machine for everyday tasks.

Re:Don't keep us in suspense (1)

Colin Smith (2679) | more than 9 years ago | (#12723307)

I read the article and basically decided that the authors were a bunch of overpaid muppets with too much time on their hands.

e.g.
http://www.transmeta.com/success/desktop.html [transmeta.com]
http://www.transmeta.com/success/workstations.html [transmeta.com]
http://www.transmeta.com/success/sbc.html [transmeta.com]
http://www.transmeta.com/success/server.html [transmeta.com]

etc etc etc.

Re:Don't keep us in suspense (4, Insightful)

pla (258480) | more than 9 years ago | (#12723350)

a very fast, very hot modern processor (in this case an AMD Athlon 64 4000+)

Very hot? If you haven't already bought one, just make sure to get one with a Winchester or Venus core.

Using C&Q, mine (only a 3000, but "close enough" to make my point) could probably get away with purely passive cooling. Using a meter at the plug, it draws a whopping 54 watts average, with 48W idle (C&Q engaged) and 65W max.

Thanks to modern CPU power saving technologies as implemented in all newer Athlons and Opterons, or Pentium M, you really don't need to sacrifice peak performance for the sake of power and heat. They deal with usually sitting there idle fairly well, by throttling back, without needing to resort to such (relatively) drastic measures as "suspend" and "hibernate".


I do, however, see one possible use for underclocking... When you keep your CPU always pegged at 100% (running Seti @home or the like, for example). Then, underclocking would allow you to trade a little bit of performance for a lot of power and heat reduction.

Re:Don't keep us in suspense (4, Interesting)

pla (258480) | more than 9 years ago | (#12723403)

it draws a whopping 54 watts average

Oops... Just to clarify, the entire system, including power supply losses, draws that much. The CPU itself, from what I've read (published numbers seem to vary a LOT, and I'd love to see some hard data on the min, mean, and max draw of the 90nm Athlon 64s), only eats between 7 and 35W (for comparison, the Pentium III line came in at the low 30s) with a theoretical max somewhere in the 60W range.


Kinda funny, actually... When everyone talks about needing bigger and better power supplies, with 400W considered a bare minimum and 600W not all that uncommon these days, I upgraded from an old P-III system and the total power consumption of the system dropped by half.

Idle? (2, Insightful)

CustomDesigned (250089) | more than 9 years ago | (#12723503)

My system is never idle. It runs seti@home and/or folding@home 24/7 in the background. So I don't think the power saving features will work for me if they depend on the processor being idle. I bought a Dell 500SC for home. It has been rock solid, but the fan is very noisy, and the DMA on the secondary IDE is busted (chipset bug). When I upgrade, I don't care about bleeding edge performance, I want it to be quiet. Wouldn't you know, after I bought the 500SC, Dell came out with the 400SC, which I've installed at several customers. That thing is quiet as a mouse. Sigh. I thought about switching and telling them, "See, 500 is better 400!"

Re:Don't keep us in suspense (2, Informative)

Brian Stretch (5304) | more than 9 years ago | (#12723506)

If you haven't already bought (an AMD Athlon 64 4000+), just make sure to get one with a Winchester or Venus core.

Nitpick: the 90nm 4000+ is a San Diego core. 1MB L2 cache is San Diego, 512MB L2 90nm E3 core is Venice, D-series core is Winchester (older 3000+ to 3500+). (You have to be this geeky to get a 4-digit /. ID. It's a law.)

I did the same thing you did. I've got a Winchester core 3000+ in my 64-bit Fedora Core server. You can cut power consumption even more with a high efficiency power supply, Seasonic S12's being the absolute best (Newegg carries them). They made a very noticible difference over the Antecs I used to use. Using a 6600GT rather than a 6800GT video card made a huge difference too.

Re:Don't keep us in suspense (1)

Txiasaeia (581598) | more than 9 years ago | (#12723539)

You mean "Venice" core.

Low-power computer with commodity parts (2, Insightful)

tepples (727027) | more than 9 years ago | (#12723279)

If you want low power you can buy systems specifically designed to perform well on low power supply.

The article is about researching how to build such systems out of cheap commodity parts, unlike the proprietary, often Windows-only parts found in laptop computers.

Re:Low-power computer with commodity parts (1)

mbyte (65875) | more than 9 years ago | (#12723342)

Hmm, a athlon64 4000 is not exactly cheap, and the recent "notbook" boards like the aopen i855 work perfectly under linux, even with speedstep. (my 1,7 Ghz doltan currently running perfectly smooth at 600 Mhz, and will get faster if i utilize the cpu)

So .. what's the point in underclocking an expensive CPU ? Rather than buying a CPU which is specificly designed for the task ?

Re:Low-power computer with commodity parts (1)

Colin Smith (2679) | more than 9 years ago | (#12723375)

Via and Transmeta do commodity boards and CPUs for low power systems. No fans, minimal cooling needed and yet still with decent performance. This article is *just* *plain* *dumb*.

Pentium M for the desktop! (1)

Dogtanian (588974) | more than 9 years ago | (#12723425)

The article is about researching how to build such systems out of cheap commodity parts, unlike the proprietary, often Windows-only parts found in laptop computers.

(The UK) Personal Computer World have an article in the current edition about using the 'Pentium M' processor in desktop machines. Mobos *are* available that support these (Abit IIRC); as well as adaptors that allow certain ordinary P4 motherboards to accept a Pentium M.

For my money, these look like a good compromise between the micro/nano-ATX mobos that take up little space and require no fans (no heatsink?), but have slow and un-upgradeable processors, and your average P4 system that sounds.... like a jet taking off.

As power requirements are low, I assume a low-powered silent power supply would do fine. I'd certainly consider this option for my next PC; I'm sick of the amount of noise my computer makes.

Re:Don't keep us in suspense (5, Informative)

The Original Yama (454111) | more than 9 years ago | (#12723318)

I have an Athlon 2100+ which I bought back in 2002 when it was brand new. After installing it, I experienced frequent lockups as the CPU overheated under heavy loads. I bought a new heatsink/fan combo (a Thermaltake Volcano 9, which was pretty good at the time) to replace the standard AMD one, but it sounded like a jet turbine at full speed and it only alleviated the problem a little. After that, I underclocked my FSB by only 3MHz (133MHz to 130MHz) and I haven't had a lockup in over a year. The associated drop in performance is unnoticable.

Re:Don't keep us in suspense (0)

Anonymous Coward | more than 9 years ago | (#12723543)

Just fit a couple of cabinet exhaust fans instead. The psu fan alone won't shift enough air to cool a recent system, so you have all fans working at max capacity.

Re:Don't keep us in suspense (2, Insightful)

PsychicX (866028) | more than 9 years ago | (#12723326)

I don't get it. If you wanted a low power system, why would you buy the top chip and underclock it?

The Athlon64 4000+ is a Hammer chip, iirc. It's manufactured on a 0.13nm process, and is a slightly older core. Instead of using that chip, why not use the Athlon 3800+? The Winchester and Venice cores are both 0.09nm chips, and run much, much cooler and dissipate much less heat than the Hammer cores. And you can use AMD's Cool n Quiet (aka PowerNow) technology to back off the processor speed to half speed automatically, when the processor isn't seeing heavy use. Coupled with a utility like RMClock [rightmark.org] on windows or a custom written utility on Linux (if your 2.6 kernel has the necessary options enabled, you simply have to write to some files in /sys), you can undervolt the chip even more than AMD's driver allows. My Athlon64 3200+ spends most of its time at 1 volt, 1 GHz, and it runs at ambient temperature. That's right, the heat generated is so little that on a stock cooler, the processor does not raise its own temperature significantly. And if a 3800+ with CnQ is too powerful, you can back down to the 3500, 3200, or 3000 models, depending on your exact needs.

Problem solved, and without several pages of blathering about underclocking.

New fab advances (1)

ag-gvts-inc (844888) | more than 9 years ago | (#12723383)

0.09 nanometers?? Wow!

Yeah, I know what you meant. Sorry I couldn't resist...

Re:Don't keep us in suspense (1)

rpozz (249652) | more than 9 years ago | (#12723605)

It will definitely make your system more stable. Unless you do something stupid with a refrigeration unit and/or very expensive water cooling, overclocking will make no percievable difference apart from a small increase in a synthetic benchmark.

If, however you underclock your FSB by just a small amount, it will make both your CPU and your memory more stable and dissipate less heat, and you won't notice any percievable performance difference. It will also mean that those components are substantially less likely to ever fuck up.

next article (5, Funny)

Arctic Dragon (647151) | more than 9 years ago | (#12723215)

Their next article: how to remove 2 cylinders from your Ferrari's V12 engine.

Re:next article (4, Informative)

TERdON (862570) | more than 9 years ago | (#12723324)

Actually, the parent poster is more insightful than the mods have thought (modded +4 Funny right now). There actually are engine control systems for motors with more than 4 cylinders that automatically turn off a few cylinders when running at low load. That moves the working point for the remaining cylinders to a more economical point (ie running at very low load is very inefficient), saving fuel (but not as much as when choosing a smaller motor - but maybe you just need the power sometimes etc).

Re:next article (2, Informative)

Arctic Dragon (647151) | more than 9 years ago | (#12723385)

Cadillac first tried that over 20 years ago with poor results (Wikipedia article [wikipedia.org] ).
GM trucks now have this (now much-improved) technology, as well as Chrysler's Hemi, as someone else posted earlier.

Re:next article (1)

Andy Gardner (850877) | more than 9 years ago | (#12723474)

Interesting, to stay on topic (or off topic) with an automotive analogy. Wwhy not have a system similar in principle to Honda's variable cam system. Monitor system resourse's and usage and dynamically clock processor speed to suit application requirements. This could be useful in a laptop where power consumption limits the length of time before your battery dies. For simple word processing, underclock the CPU to increase battery life. Then up the clock speed as required for gaming etc. It will probably only save a few watts but every bit helps.

Re:next article (1)

TERdON (862570) | more than 9 years ago | (#12723496)

This is already being done, AMD's version is called Cool 'n Quiet, and is being deployed as well in notebook A64s and in workstation A64/Opterons. Similar systems are already available for Pentium M (not P4 though, IIRC), and in Macintoshes with G4s (anyone knows about G5?).

Re:next article (2, Interesting)

DrEldarion (114072) | more than 9 years ago | (#12723325)

The new Chrysler Hemi automatically selects how many cylinders it's going to use based on how you're pushing it. Flooring it? Use all 8. Just cruising? 4 is fine. I suppose that would be more related to AMD's Cool'N'Quiet, though, which is a wonderful feature. 800MHz for web browsing is more than enough, but when I'm playing games, use full power.

Anyway, did you see the size of that heatsink? It looks like a small-scale modern office building.

Easier solution: Just run windows (4, Funny)

carcosa30 (235579) | more than 9 years ago | (#12723219)

Most modern processors and motherboards can just as easily run under a rated speed as it can run over...


Microsoft operating systems and software accomplish this without all the work.

Re:Easier solution: Just run windows (1)

m85476585 (884822) | more than 9 years ago | (#12723293)

No. They just simulate it. They still use the CPU at full speed, but make it appear lower. The same amount of heat as running it under full load is generated, even if the system is "idle".

Re:Easier solution: Just run windows (-1, Troll)

carcosa30 (235579) | more than 9 years ago | (#12723361)

You know, I used to think all the microsoft bashing that goes on on slashdot was kind of silly. I mean, I agreed with it, but after all, the OS was necessary, wasn't it?

Now I wonder what's going on under the hood there that takes so much processor time. And why does it grind your drives the way it does? Why do the drives have to tick all the time writing to the FAT table, et cetera? It's not because of spyware. Microsoft does this on a freshly installed machine not connected to the net and with no software installed.

I don't get it.

The worst part of it is the fact that XP is the most end-user usable OS they've ever released. And it's still shit.

Re:Easier solution: Just run windows (0)

Anonymous Coward | more than 9 years ago | (#12723436)

is that coming from a gentoo fanboy??

Fast and Fanless would be nice (1)

HighOrbit (631451) | more than 9 years ago | (#12723227)

Unfortunately... performance and heat seem to move proportunately. I would love to see (or hear) a silent server room. Hmm... maybe with embedded systems getting more powerful this will one day be a reality.

MIPS per Watt (1)

Colin Smith (2679) | more than 9 years ago | (#12723251)

Look it up on Google, you could have a near silent server room today. AMD and Intel suck, literally (power & AC).

Re:Fast and Fanless would be nice (1)

N3TW4LK3R (841526) | more than 9 years ago | (#12723271)

Unfortunately... performance and heat seem to move proportunately.

actually, the article's conclusion is that this is not the case.

what a completely useless review! the point is that you have to make the CPU 60% slower in order to make it 20% cooler.

why would anyone want to pay 400$ on a CPU then have it perform like a 50$ CPU just to win 2dB's of cooling sound?

Re:Fast and Fanless would be nice (1)

Paiway (842782) | more than 9 years ago | (#12723557)

Dude, who gives a flying fuck about the noise level in a server room? It's not like anyone is going to work in there anyway, and some mild noise for 3 mins while rebooting that damn IRC server is completely acceptable.

Underclocking makes sense to me (4, Insightful)

Dolphinzilla (199489) | more than 9 years ago | (#12723239)

If you are designing a system for high reliability, under temperature extremes and such (military environments for example) underclocking is the way to go - you can minimize power and heat loads as well as potentially avoid timing instabilites that occur when you push a processor to the performance margins.

Re:Underclocking makes sense to me (1)

delicious (879639) | more than 9 years ago | (#12723316)

I agree, underclocking has a wide variety of applications. I was thinking of google's server farms where the number of computers failing per day is in the double digits. If they underclocked processors as a rule they might save both money and performance.

Re:Underclocking makes sense to me (0)

Anonymous Coward | more than 9 years ago | (#12723390)

Yes. They'll save money by buying expensive processors that run at high speeds, then somehow save performance by underclocking them...so that they don't...perform as well...

Really, did you even read what you were posting?

Er, did they hear about Cool'n'Quiet? (3, Insightful)

marat (180984) | more than 9 years ago | (#12723243)

I thought what they are testing is the whole point of AMD Cool'n'Quiet technology, but they don't even mention it in the article! Nice try reinventing the bicycle. I'm already underclocking my Athlon 64 right now, thank you.

Umm.... (1, Informative)

sagenumen (62467) | more than 9 years ago | (#12723247)

Couldn't you just buy a slower processor? Why buy a more expensive processor just to have it match a slower (read: less expensive) processor's performance?

Re:Umm.... (4, Interesting)

Xshare (762241) | more than 9 years ago | (#12723278)

I think the point is that these "better" processors were built with that larger processor speed in mind, and if you underclock it, you still get the added benefit of somethign that's supposed to cool and use a bigger processor for a smaller one. It's like... AMD when they build the 4000+ over the 3200+, attempt to make the 4000+ as calm and quiet as possible, within limits, and go farther with the 4000+ than with the 3200+. Now if you underclock the 4000+, you still take advantage of that extra technology...

I'm probably wrong.

Re:Umm.... (1)

SharpFang (651121) | more than 9 years ago | (#12723290)

RTFA?
No. You get a slower processor that runs about as hot as the new one, drains about as much power and crashes on overheating by about the same interval. But if you downclock the faster one, you can run it at speed of the slow one, with power usage lower, overheating threshold higher (say, saving on air conditioning?), and possibly with smaller, quiet fan.

Re:Umm.... (1)

Ateryx (682778) | more than 9 years ago | (#12723381)

Every time I help a friend build a computer they've needed a bigger/more powerful power supply than the guy before. We're not just talking about wattage here--you also need enough amps across the rails.

If you wanted to get a faster processor and lower its speed for daily use, you're saving on your energy bill. I wonder how long it would take you if you brought a 4000+ to 2800+ speeds to save enough on your energy bill to pay off the cost of the faster processor. We have to assume they both use the same amount of energy when running at full speed, which seems to be okay for the situation.

Re:Umm.... (2, Insightful)

ccccc (888353) | more than 9 years ago | (#12723413)

Well, the whole point for Cool & Quiet is that this can be done dynamically during run-time. It's quick and painless for your fast processor to slow down when you don't need the horsepower. The slower processor can't suddenly become faster if you need it.

Laptops? (1)

Kerhop (652872) | more than 9 years ago | (#12723248)

I could see where the power drain and heat would be reduced for use in a laptop or other mobile device that runs on batteries. Currently chip makers have two separate cpu's for desktop and laptop but might save in production costs to manufacture just one for use in both systems.

Re:Laptops? (1)

anderm7 (68050) | more than 9 years ago | (#12723294)

A lot of times they do this very thing.

1.4Ghz, 2.4 Ghz, 3.4 Ghz Pentium III are all the same chips, they are just fail built in tests at different places.

The upside is that the 1.4 Ghz chips, provided the PLL can run that slow, will be much lower power, and you can still sell them.

The reason they come up with different chips, is to make much, much lower power chips.

Re:Laptops? (1)

m85476585 (884822) | more than 9 years ago | (#12723310)

My 2.2 GHz Celeron laptop is slow enough. But underclocking it might make the batterie last longer than 2 hours.

Re:Laptops: Variable voltage/speed controller (1)

G4from128k (686170) | more than 9 years ago | (#12723391)

What laptops need is a variable voltage and speed controller. A bit of calibration software would map the lower-boundary of core voltage versus speed (maybe as a function of temperature, too) and then use that calibration data in daily operations. The machine would constantly regulate both core voltage and clock speed.

Re:Laptops: Variable voltage/speed controller (1)

SirTalon42 (751509) | more than 9 years ago | (#12723570)

So... it would be a Transmeta processor?

Low power AND low temperature is easy! (0, Flamebait)

jebilbrey (764968) | more than 9 years ago | (#12723255)

PC Stats actually took this idea from me. I took the same processeor, unplugged the computer (to lower power consumption) and then stuck it in a freezer (to lower temperature). Wow! Also nil power consumption (the freezer uses some to keep it cool) and the temp is really low! Next I'm going to try this with my laptop because the bottom of it gets really hot!

What about underclocking? (1)

Varun Soundararajan (744929) | more than 9 years ago | (#12723267)

Underclocking is a real good thing, if you want to save your electricity bills, plus, you dont want to run your computer faster when there is no need to. Consider a case where you use your amd64 for both browsing and occasional scientific computations. You want to run it at its full speed (and consume how much electricity it wants to) only when you use it for computations. Otherwise, clicking on the back and forward buttons of firefox doesnt need a 4000+ system. It is very important to understand that the underclocking is as important as overclocking, given the fact that most people in the corporates want the fastest computer on earth for sending emails and solitaire

Re:What about underclocking? (1)

leon.gandalf (752828) | more than 9 years ago | (#12723360)

WOW, does this meen my next machine will have a TURBO button on it like back in the early 90s?

Re:What about underclocking? (0)

Anonymous Coward | more than 9 years ago | (#12723433)

Wow, you described just about every notebook on the market today!

Want a cookie?

PowerNow (1)

ag-gvts-inc (844888) | more than 9 years ago | (#12723270)

Is it really a surprise that the proc will run stably underclocked [amd.com] ?

They've been doing this at the factory for some time now.

What's the point with passive cooling... (2, Insightful)

TERdON (862570) | more than 9 years ago | (#12723275)

... if there are annoying fans on the motherboard as well as on the GPU?

You would think the whole point gets moot - the system certainly won't be quiet. (I believe there is an actual need for quiet systems eg in recording studios etc - which make the article interesting, but not great).

Re:What's the point with passive cooling... (1)

m85476585 (884822) | more than 9 years ago | (#12723328)

Hard drives are also noisy, but you usually can't hear it over case fans. I replaced an old 8.5Gb drive once and the computer is now half as loud.

Re:What's the point with passive cooling... (1)

SharpFang (651121) | more than 9 years ago | (#12723338)

You'd hardly ever need to downclock a client/gaming machine. You do this with a server. A server doesn't need a fast GPU, so no need for a fan on it. Downclocked CPU means whole system downclocked, so you can apply passive cooling to the motherboard. There's still a problem with the PSU, but use one with some 200 spare watts, and spin its fan down using, say, a resistor in series, so it works quietly.
If you want a quiet desktop, use water cooling. For everything.

Re:What's the point with passive cooling... (2, Interesting)

TERdON (862570) | more than 9 years ago | (#12723364)

Yes, I also realize this. Should have put an [/irony] at the end, perhaps. :)

My point was that in TFA (oops - we're on Slashdot, no one have read it) they use use some high-end Radeon and a motherboard with one of those annoying northbridge fans, mooting the point of a quiet CPU cooling setup alltogether. Not really the setup you (and I) are suggesting...

Re:What's the point with passive cooling... (1)

SharpFang (651121) | more than 9 years ago | (#12723448)

Not mooting the whole point of downclocking though - still power saving, more stable work, higher safe temperature interval...

Re:What's the point with passive cooling... (1)

TERdON (862570) | more than 9 years ago | (#12723513)

Yes, but you don't really have to buy a $50 (or whatever the price is of that massive metal piece) passive cooler to do that, as they used . You can do it with coolers with fan on them too. Preferably temperature controlled ones...

That would actually be cheaper, leaving money for a quiet GPU cooler or something. Or a passive heatsink for the nb...

Re:What's the point with passive cooling... (1)

Thag (8436) | more than 9 years ago | (#12723396)

Not every motherboard has a northbridge fan. Thank goodness.

Re:What's the point with passive cooling... (1)

TERdON (862570) | more than 9 years ago | (#12723409)

The one in TFA does. (Yeah, should have realized I'm on /. and the PDF of people really reading TFA is a constant equal to 0.02...)

Re:What's the point with passive cooling... (1)

Thag (8436) | more than 9 years ago | (#12723432)

True, but if you're going to do this right, you would obviously either buy one that doesn't, or replace that heat sink with a larger passive one.

I'm actually running a quiet box for my backup pc, and I made sure the MB didn't have a fan.

I've had good results running with a cheap Duron processor (I think it's 1.4 running at 1.2), a big Zalman cpu cooler, and an Antec Sonata case. I use a GeForce 5200 (NOT Ultra) video card, which is cooled with just a heat sink and no fan.

Re:What's the point with passive cooling... (1)

TERdON (862570) | more than 9 years ago | (#12723445)

I agree with you. I was trying to show that they were doing it the wrong way in the article...

Well, peace, love and Elvis. Everybody agree except TFA.

Oblig. Futurama Quote (1)

theridersofrohan (241712) | more than 9 years ago | (#12723277)

Most modern processors and motherboards can just as easily run under a rated speed as it can run over... but is there a point to this? Well possibly.



My gut instinct tells me.... Maybe!

Not useful information? (3, Insightful)

erroneus (253617) | more than 9 years ago | (#12723281)

I think it is somewhat useful information. While most people are thinking about how much faster you can process, many of us are looking to reduce the noise of fans blowing. I recall when 800MHz was a fantastic speed... hell, for that matter, 300MHz was pretty nice too depending on how far back you go.

And are we really using all of those cycles? Not really. Right now, a system's performance (IMHO) is largely the responsibility of the quality of RAM, Video and system board stuff. After all, what "feels" fast must be fast. If I've got a slow hard drive, then it's a slow system and if I can accellerate the video, then it's a slow system. What good is 4GHz if you've got a slow everything else... and by the same token, if you've got a fast everything else, a 2GHz processor is probably plenty.

Re:Not useful information? (1)

crimoid (27373) | more than 9 years ago | (#12723410)

> 800MHz was a fantastic speed... hell, for that
> matter, 300MHz was pretty nice too depending
> on how far back you go.

Heh. I remember getting excited over a 386.

Hell, moving from my C64 to a 286 was fun but I was too young to appreciate it.

Re:Not useful information? (0)

Anonymous Coward | more than 9 years ago | (#12723542)

heck, i overclocked my acorn electron from 1mhz to a whopping 2mhz

eat that

--lazy

been there, done that, it works, no surprises here (2, Informative)

tota (139982) | more than 9 years ago | (#12723284)

I decided to underclock some 1U systems (~XP 2500) to ensure that they would never overheat (longevity was more important than performance).

It works perfectly: a drop of 20% in core clockspeed greatly reduced the heat output, the core temperature dropped by almost 10 degrees C.

Why didn't you just buy slower systems? (1)

Colin Smith (2679) | more than 9 years ago | (#12723355)

Cos by buying a 1U system with a slower CPU in the first place you could have saved money as well as reducing the temperature and power requirements.

Re:Why didn't you just buy slower systems? (1)

imroy (755) | more than 9 years ago | (#12723517)

Not necessarily. The higher-rated processors are often made with a smaller process. This is the reason they can operate at the higher clock speed without overheating in the first place. This A64 4000+ is probably (?) the first in a new line made with a smaller process.

Re:Why didn't you just buy slower systems? (1)

TERdON (862570) | more than 9 years ago | (#12723574)

Actually, AMD introduced the new 90 nm processes from below, starting with 3200+ et al. That had probably to do with process tweaking - even though the processors where running at lower power, they were'nt quite reaching the same frequencies at that time. You also sometimes see this with GPUs - ATi seems to do it with their Radeons quite often.

One reason for this might be that the lower yield rates necessary with smaller chips (less L2 Cache in AMD processors, less pipelines in ATi GPUs), making them less process sensitive. Basically, with physically smaller chips, there is less risk of having a defect "hit" the chip, making it possible to use a somewhat more immature process (which haven't reached high yields yet). Also, a "small" defect might not have the same effects in low-end chips, running at lower frequencies.

Basically, they're using low-end as a process tryout.

Re:been there, done that, it works, no surprises h (0)

Anonymous Coward | more than 9 years ago | (#12723393)

From the article:
"To put it another way, for a 66% drop in speed there was a 20% drop in temperature. This makes a bit more sense if you look at the numbers in terms of Voltage not speed; a 43% drop in voltage producing a 20% drop in heat seems more reasonable."

Utter non-sense.

Why do people not understand that temperature is a relative measurement? and that 0 deg C does not really mean much? especially measuring percentage?

dropping from 33.5 C to 26.9 C is not really a 20% drop in temperature, if you convert it to Kelvin then it's only some 2-3% drop? The correct way to quantify this is to measure the drop against the ambient temperature, which I assume is somewhere around 20-25, then the drop of would be a lot more significant.

If going by the author's logic, does he mean that if we could somehow expect to achieve 100% drop in temperature by not applying any currents and get a freezer block? and thus violating laws of thermodynamics and creating a warp in space-time continuum and leading to the end of universe?

Darn, I knew I shouldn't have turned that computer off...

Sweet (1)

Abit667 (745465) | more than 9 years ago | (#12723285)

First thing i'd do when I get a brand new $473 cpu...

Their Maths is a little suspect in places (5, Insightful)

kabbor (856635) | more than 9 years ago | (#12723292)

They listed the drop in temperature from 33.5 to 26.9 as a 20% drop. However, they didn't mention the ambient temperature. If you take 20 degrees, then this drop is more like 50%. That would also mean that it was consuming well under half the power. (I'm assuming watts->degrees is exponential.)

As a secondary matter, the person who got me interested in BSD, as a rule, made his servers with whatever was the cheapest AMD-K6, underclocked to 350MHZ. Bulletproof boxes with long lifetimes. I'm sure there are still some churning out the bits around this town.

Celsius percentage change is meaningless (1)

NextGaurd (844638) | more than 9 years ago | (#12723327)

Claiming percentage change in temperature in Celsius is meaningless...it's not an absolute temperature scale like kelvin.

Re:Celsius percentage change is meaningless (1)

kabbor (856635) | more than 9 years ago | (#12723376)

True: I just made that point, slightly tongue-in-cheek, to another post. What really matters is the relative difference between the sink and the air outside.

Re:Celsius percentage change is meaningless (1)

NextGaurd (844638) | more than 9 years ago | (#12723418)

You're right. I should have acknowledged that and made it clear my criticism was of the original article for bringing up the topic of percentage change in Celsius temperature.

Re:Their Maths is a little suspect in places (1)

Brooklynoid (656617) | more than 9 years ago | (#12723358)

They listed the drop in temperature from 33.5 to 26.9 as a 20% drop. However, they didn't mention the ambient temperature. If you take 20 degrees, then this drop is more like 50%.

Your logic is a little suspect as well, I think. An ambient temperature of 20 degrees C is based on an arbitrary (for our purposes) zero point that's really 273 degrees above absolute zero, so performing comparisons based on that arbitrary zero point doesn't tell us very much at all. If we decide that a computation of the temperature drop as a percentage of ambient temperature is of interest, we should perform that computation using the Kelvin scale.

Re:Their Maths is a little suspect in places (1)

dankelley (573611) | more than 9 years ago | (#12723402)

Actually, it makes sense to calculate temperature anomalies relative to the ambient because a device using NO power would BE at the ambient temperature. The original post made no sense. The Brooklynoid followup does. However, such calculations are very sensitive to the background temperature used. (Try putting 26.9C as the background!) Such experiments must always involve measuring the ambient condition.

The original poster agrees wholeheartedly.... (1)

kabbor (856635) | more than 9 years ago | (#12723460)

..and, indeed, thought that the importance of ambient temperature was the whole point of his post....

mod parent up, please. The power dropped 4 times (0)

Anonymous Coward | more than 9 years ago | (#12723597)

The parent post is right. Without ambient temperautre, the results are meaningless.

Looking at the voltage levels, it is obvious that slowing the clock twice, allowed for about 4 times less power! The article didn't even mention that. The experiments were good, but the guys that did them failed completely in their conclusions.

There is a point... (3, Insightful)

chihowa (366380) | more than 9 years ago | (#12723302)

On all of my personal must-stay-up servers, I get a processor that is too beefy for the task it's to do, then clock it down. It's usually rock solid and runs very cool. In some cases I've been able to get by using only passive cooling and still keeping the processor very cool, making the system solid, cool, and nearly silent.

Myself here... (1)

SharpFang (651121) | more than 9 years ago | (#12723304)

...running a server on 486DX80 downclocked to 66MHZ. Original fan+radiator replaced with a radiator alone. From an Athlon.
(several more power savings in the system - like not using a CD drive, and the power supply runs just fine with its fan switched off. So, a fanless config.

I know a way (3, Funny)

Shinaku (757671) | more than 9 years ago | (#12723309)

If they want to underclock a 4000+, they could just swap me my 3000+.. I wouldn't complain.

power management (1)

cahiha (873942) | more than 9 years ago | (#12723322)

That's what CPU power management is for: it allows you to select in software what tradeoff between performance and power you want. I believe most (all?) of my desktop machines have it built in.

Faulty Analysis? (4, Insightful)

Brian Blessed (258910) | more than 9 years ago | (#12723330)

The temperature measurements in the article don't seem to be relative, and yet they say things like this:
for a 66% drop in speed there was a 20% drop in temperature.

In this context, talking about a 20% drop in temperature in degrees celsius makes no sense for comparison purposes. They go on to state that "a 43% drop in voltage producing a 20% drop in heat seems more reasonable", but this is assuming that the temperature drop corresponds to a equal reduction in heat output.

- Brian.

Re:Faulty Analysis? (0, Redundant)

kabbor (856635) | more than 9 years ago | (#12723366)

20% drop in temperature. But it isn't, is it? 33C to 26C is 306K to 180K. That's like 3% drop. Of course, they should have compared it to the ambient temperature. Then the drop is a usefull 50%!

Bragging rights... (2, Funny)

Alsee (515537) | more than 9 years ago | (#12723332)

ExXXtreem underclocker bragging rights post...
I've got my system cranked to 200 millhertz!*
Beat that ya loozers!


* Footnote: No system stability problems detected yet.
I'll post a confirmation follow-up when the standard stability test suit finishes running.

-

Re:Bragging rights... (1)

kabbor (856635) | more than 9 years ago | (#12723397)

One clock cycle every 3+1/3 minutes: I think it's going to take some time.

Re:Bragging rights... (1)

shobadobs (264600) | more than 9 years ago | (#12723440)

That's one clock cycle every five seconds (200 millihertz = 0.2 hertz).

Re:Bragging rights... (1)

kabbor (856635) | more than 9 years ago | (#12723489)

Ooh, um, Yeah, right. (digs hole, jumps in.)

Mistake (2, Insightful)

Richard_J_N (631241) | more than 9 years ago | (#12723335)

They have measured the (absolute) celcius temperature of a well-cooled system, without quoting the ambient temperature. Then, concluding that the temperature hasn't droppped much, they assume the power hasn't dropped much.

The correct measurement is the *difference* in temperature between the CPU and the ambient air. Power dissipation is linearly proportional to this.

Underclocking for Gaming, Reverse Logic (2, Interesting)

Anonymous Coward | more than 9 years ago | (#12723367)

From 99-03 I always underclocked my AMD CPUs for gaming, the minimal requirements necessary for playing everyones favorite Counter-Strike, and my undying urge to make my CPU last ages kept my system running smooth, my latest underclocking was from a 2800+ 2ghz AMD down to a 1.87ghz miracle machine that ran on a minimal fan system, never overheated and my record uptime was 3 months and 2 weeks ;D

For the *clocking newbies... (-1)

Anonymous Coward | more than 9 years ago | (#12723377)

How do you do this anyway? is it easy?

I'd like to do it on my homebox.... I want it to last for a long time and I don't really care about speed since I am perfectly happy using a 1ghz processor (my laptop), and I'm currently using a 2600+ amd.

Use CrystalCPUID to manage speed and voltage (4, Informative)

Brian Stretch (5304) | more than 9 years ago | (#12723442)

Use CrystalCPUID [crystalmark.info] to manage your AMD64 CPU's speed and voltage rather than the default Cool 'n Quiet power management (set your Power Scheme to "Always On" to disable that, definitely leave the CnQ driver installed). On most HP AMD64 notebooks we've found that you can usually safely set the core voltage at about 0.2V below stock at full speed. Judging by the AMD Thermal Design Guide, that's enough to cut power consumption nearly in half. I swapped in a Mobile-class Athlon 64 3200+ into my Pavillion zv5000z in place of the stock DTR-class chip and have been running 1GHz at 0.8V, 1.6GHz at 1.025V, and 2GHz at 1.225V for months. That puts the full speed power consumption at slightly above AMD Turion ML levels. For the stock DTR chips, 1.3V at full speed is popular.

Of course, in average use, the standard AMD Cool 'n Quiet behavior of running 800MHz at 0.95V while idle will give you battery life that's almost as good as an undervolted setup. 3-4 hours of battery life with a 12 cell battery is common, versus a fraction of that for the poor bastards who bought the P4-based zv5000 series (HP wisely dropped Intel CPUs from their zv6000 line). Undervolting does wonders under heavy CPU load though.

MobileMeter [geocities.co.jp] is my favorite way to monitor CPU speed and temperature, and Hot CPU Tester Pro [7byte.com] verifies that I didn't go too far.

Why? (0, Redundant)

michelcultivo (524114) | more than 9 years ago | (#12723472)

Why you underclock your processor if the amazing thing is to overclock and see if you can cold them without loosing it.

CPUFreq? (1)

MarkByers (770551) | more than 9 years ago | (#12723490)

Doesn't using CPUFreq with a powersave governor have the same effect as underclocking the CPU in the BIOS? What's the advantage of doing it the way suggested in the article?

Re:CPUFreq? (1)

tomstdenis (446163) | more than 9 years ago | (#12723504)

the cpu can only go within some ranges. Like mine can go from 1.5v @ 2.2Ghz down to 1.1v @ 1Ghz ... what if you want to run at 0.9v at say 500Mhz? ...

But at that point if you have to reboot to go into "powersave" mode ... just buy via box or something.

Tom

ShTit (-1, Troll)

Anonymous Coward | more than 9 years ago | (#12723545)

I usually underclock my servers (1)

dyfet (154716) | more than 9 years ago | (#12723547)

I usually underclock my servers here when I expect them to be left alone/unattended, such as in a phone closet, and just expect them to be always up. Most tasks are not that compute bound, especially not the ones I might typically setup a small server for, such as an internal file server, internet packet routing, or a phone control system.

The benefit for heat reduction (and less thermal sensitivity in an enclosed space) is often a worthwhile tradeoff over a server I can just leave alone and expect to run for years at a time.

CPU Frequency Scaling (1)

_aa_ (63092) | more than 9 years ago | (#12723580)

Isn't this what CPU Frequency Scaling [amd.com] is for? I personally use the ondemand scaling governor made available in linux kernel 2.6.10, I believe.
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