Riskfree to underclock (not overclock) a CPU?

Raffe

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Apr 1, 2002
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Around AMD XP2000 performance-level is more then enough to satisfy my future needs for computing power, I think. Im NOT quite happy with its excessive heat-produktion and screaming-fan cooling requirements however.

I was thinking:

Is it viable to upgrade to a future more powerful CPU (lets say an AMD Barton XP3000) - then deliberately <i>underclock</i>, or strangle this beast back to XP2000-2200 levels: just in order to achieve much lower heat-production thanks to the more effective layout/design + a larger core compared to T-breed + the 0.13 technology?

Is underclocking easy and problemfree? I have heard that one must "lock up" the CPU in order to overclock. But must one do that then <i>underclocking</i> also? Or is it enough to jump straight in to BIOS and turn off auto-configuration and change the multiplier (for example) manually? What parameters should one change in order to get the best underclocking-results? (= lowest heat-produktion; quietest cooling-needs).
 

Scout

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Dec 31, 2007
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Okay.. the term is "unlock" the CPU in order to overclock, not "lock up"! Actually, unlocking Athlon's used to be quite easy, but with the Athlon XP's it is difficult. The new Thoroughbreds SHOULD be the same as the XP's, but not sure on that yet... They are too new.

Underclocking is easy and does produce less heat as you suspected. In addition, you can sometimes turn down the core voltage a bit if you underclock and that too reduces heat production even more. Unfortunately, the only way to do it really (unless you're willing to try and unlock your chip) is to reduce the front side bus speed, and in doing that, you lose memory performance as well.

The FSB speed on Athlon's today is 133 X 2 or 266 MHz. You can drop this anywhere from there down to 100 X 2 or 200 MHz. (or even slower I guess if you want to...)The processor will run fine and be cooler, but much slower!

With my old fire breathing Athlon T-bird 1.4 which was unlocked, on really hot days I'd have to slow it down to 1200 MHz. or even 1 GHz. in order to reduce heat. With that chip, I could never reduce the core voltage or else it wouldn't boot. But it did run significantly cooler at those speeds. (OK all you Intel guys... laugh it up! But that chip was really tough to cool and you had to watch the temps!)

Scout
700 Mflops in SETI!
 

Crashman

Polypheme
Former Staff
If you drop your bus speed to 100MHz, you should be able to drop your voltage significantly, and end up with a processor that can be cooled with even a super quiet fan.

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