Whats the maximum I can UNDER-clock an AthlonXP 3000+? To save power, for server use.

[nobb]

Currently Ive got a Pentium 2 350mhz system which I have underclocked by setting the jumpers to run at 233mhz. It is running Windows 2000 and I am using it as a home server. Power consumption is only a mere 20 watts on idle and the processor runs cool even with the fan off.

I have another machine, an AthlonXP 3000+ which I would like to see if it can run Windows Home Server (since the old one is too slow). I mostly like how easy it is to expand hard drive space with WHS. But the AthlonXP is a power hog, and I am wondering if I can significantly reduce power consumption by underclocking (currently 90 watts+, would like to reduce to <40 watts). Of course if I can underclock it enough that I can run the CPU fanless, even better. I will also probably turn off all unnecessary bios options and remove stuff like DVD drives, PCI cards, etc.

Im a newbie at this and wouldnt find much underclocking information on this processor. In the motherboard, I have options for spread spectrum, CPU FSB, CPU Ration, Vcore, DDR Voltage, AGP Voltage. I am guessing that the lower the voltage and frequency, the better. I am wondering if you guys have any tips on what precautions I should take, if any? Can you mess up a system by too much underclocking, like you can with overclocking? Will the system become instable? What are your experiences on underclocking?

 

[o1die]

You can try reducing the cpu voltage by .2 volts, and see how stable the system is. I never tried amd's cool and quiet software on a socket 462 board, but maybe it will work.

 

[Soulkeeper]

there is no set "maximum" the settings will be limited by whatever board you are using

a 20% undervolt is fairly easy to obtain with those chips (somewhere around 1.3v), if you're lucky you could undervolt it and still keep the same clock
you'll just have to play around with it, each chip is different


you could just undervolt it in .1v increments, untill it becomes unstable, then drop the clock by 100MHz or so
repeat this process untill you get the desired effect

 

[cusideabelincoln]

The mobile Athlon XPs can run at 1.45V and 1.35 and are usually under 2.0 GHz. I'd say start from there.

 

[Fox5]

From what I recall, you can downclock the Athlon XP memory bus to 100Mhz and lower the multiplier to 2x or 3x, so about 200-300Mhz is the minimum. After that, you could lower vcore to 1.1V, maybe 1V I'd imagine. Should get the cpu power usage down pretty low, though the AXPs had crap for power management, a single core athlon 64/sempron could dynamically lower its speed to its lowest support (600Mhz iirc) but run at a higher speed when needed. Running fast for short intervals can often be more power efficient than running low speed all the time since the work gets done faster.

 

[elconejito]

It's going to involve a lot of trial and error on your part to find the proper settings. It will be very similar to overclocking in that regard, just in reverse. There is probably an "easy" underclock (assuming your board supports it), but you may have to really tweak to get a "good" underclock. I'd go check out the forums at silent pc review as well. That's the majority of what they do is try to get as much power with as little heat/noise as possible.

 

[fffblackmage]

trial and error is probably the only way to go.
though with my barton core athlon xp 2600+ and shuttle nforce 2 mobo, i was able to push the fsb down from 333MHz to 266MHz, or cpu clock from 1.9GHz to about 1.5GHz, which practically made the cpu equivalent to an athlon xp 2000+. I don't remember how much i got the cpu voltage down though. In the end, while going further with underclocking/undervolting, my computer ended up suffering a bad crash, and now i cant boot into xp. The weird thing is that I was able to install xp, but can't boot into it, gets stuck at the xp logo screen. However, I can install/boot into ubuntu just fine. Just weird =/

I could do fanless with the underclock, but temps were ~60C or so? while running prime95. It was too hot for comfort is what i remember.

 

[heyheybooboo]

CrystalCPUID
- - - voltage & multiplier management

You can set 3 operable states depending upon load. It would help if you told us your mobo model. Dropping the FSB in the BIOS and using Crystal could easily drop your CPU to below 10w.

Experts in undervolting reside at Silent PC.