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AMD Athlon64 4000+ Underclocking
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.'"
Their next article: how to remove 2 cylinders from your Ferrari's V12 engine.
Microsoft operating systems and software accomplish this without all the work.
Intolerance for ambiguity is the mark of the authoritarian personality.
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.
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.
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.
"The legitimate powers of government extend only to such acts as are injurious to others." Thomas Jefferson.
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.
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.
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.
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.
If you want a vision of the future, imagine a youtube comments section scrolling - forever.
If they want to underclock a 4000+, they could just swap me my 3000+.. I wouldn't complain.
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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.
OLPC Australia
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.
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.
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.
Use CrystalCPUID 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 is my favorite way to monitor CPU speed and temperature, and Hot CPU Tester Pro verifies that I didn't go too far.
on an AsRock motherboard, yes? I've got two
2600+ systems with identical heatsink/fans.
The one in a MSI KM2M motherboard is rock-solid
stable at full FSB speed (133MHz), but the one
in the AsRock K7VT2 has to be underclocked to
130MHz FSB or else it constantly locks up.
I'm guessing your problem was never cooling,
it was getting stuck with a cheap mobo, as I did.
Ah, bitter dregs.
what I don't see very often is reviews address all the other sounds in a case, like the damn hard drives. I never hear my fans, system is water-cooled with two 120mm fans at 5v, but all nite all i hear is GRINNNNNNNNNNNNNNNNNNNNNND of the damn hard drives. Why doesn't someone address this issue and do a REAL review on how to get rid of hard drive sounds? Sure silentpc has done a few, but everyone else is like "yeah, i hear like, a fan, sometimes, so i'm gonna run my new 4000+ processor at 800mhz".
talk about unoriginal....
my karma will be here long after I'm gone
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The article states:
Unless the computer and participants were in a frozen room (at 0 degrees celcius), their analogy is flawed. The amount of heat generated is directly preportional to the temperature INCREASE above the ambient temperature. Let's assume that the test occurred at "room temperature" (70F deg or 21C deg). The chart would look more like the one below:The article should have stated:
"For a 66% drop in speed, there was a 53% drop in added temperature."
"a 43% drop in voltage produced a 53% drop in in heat seems more reasonable."
My observation from that data above:
"A drop of only 400MHz (17%) and 0.15V (11%) showed a significant drop in the amount of heat generated (25%)."
Thank you for letting me share this old-timer drivelling on slashdot.
Panurge has posted for the last time. Thanks for the positive moderations.