voltage question

[2008 IQ is unacceptable]

In vista 64 my AMD athlon 64 x2 (2.3 GHz) 45 W operates as low as 1.00 V, so it runs very cool, in fact it runs so much cooler that it makes the room feel quite a bit cooler.

But in xp it does go below 1.2V. so it runs much hotter. and the ambient temps and the mb temps are a few C higher due to the cpu running hotter.

Why does it run cooler in vista?

Is there anyway i can make it run cooler in XP?

I always have the freezer 64 pro @ full fan speed and I'm basically using the stock thermal compound (used as cleaner and surface purifier and then put on ac mx2, not realizing that was probably what was originally on the f64p.)

I have the Foxconn 790FX/SB750 board.

I will be grateful for any answers=]

 

[BRiT]

Vista has better support.

 

[Mariner]

Personally, I undervolt my CPU using the BIOS. You can then always be sure your computer is running at low voltage. Obviously this disables Cool N Quiet so your CPU doesn't also underclock when idle.

Not sure if your motherboard supports undervolting in the BIOS, however.

The alternative is to use a utility called Crystal CPUID which allows concurrent undervolting/underclocking using settings you pre-define. I understand this utility is supported in Vista.

Obviously this takes a bit of fiddling but great energy saving benefits may be worth your while - I'm intending to start re-using CCPUID if I ever get around to upgrading my motherboard - something I've been planning to do for some months now!

 

[2008 IQ is unacceptable]

Personally, I undervolt my CPU using the BIOS. You can then always be sure your computer is running at low voltage. Obviously this disables Cool N Quiet so your CPU doesn't also underclock when idle.

Not sure if your motherboard supports undervolting in the BIOS, however.

The alternative is to use a utility called Crystal CPUID which allows concurrent undervolting/underclocking using settings you pre-define. I understand this utility is supported in Vista.

Obviously this takes a bit of fiddling but great energy saving benefits may be worth your while - I'm intending to start re-using CCPUID if I ever get around to upgrading my motherboard - something I've been planning to do for some months now!

Thanks=]

I can adjust the vcore in my bios. Since I have to remove the cmos battery and then put it back in if I set the voltage too low, I have some questions to prevent me from having to do that repeatedly.

The default vcore for my cpu is 1.2V.

Would it more than likely be stable under full load with stock clock speed if i set the vcore to 1.1? if not, what about reducing the ref clock by 6 MHz (that would reduce the core speed by 69 MHz?)

going down .1V would reduce temps by at least 4-6 C, right?

 

[Mariner]

Once you've found a stable undervolt, you shouldn't need to adjust the voltage and therefore mess around with the CMOS battery.

The best way to test out if your undervolt is stable or not is to run Orthos for 12 or 24 hours. This runs a modified version of the Prime95 torture test on both cores of your CPU. If the CPU can run through this without error or failure at the undervolt you have set, you shouldn't encounter any problems in future. Here's the URL for Orthos:

http://sp2004.fre3.com/

My Athlon 64 X2 3600+ is undervolted to 1.00V at stock 1.9GHz clocks and this has never caused me any problems. It may be possible for you to keep your X2 at 1.00V too even with the higher clocks as your CPU should be of a newer stepping than mine and capabilities tend to improve as new steppings are released.

For further information I suggest you check out this thread at SPCR which should give you some kind of idea what undervolts can be achieved with these chips.

If you decide to use CCPUID or RMClock to undervolt/underclock using software you will find plenty of information on SPCR as well. I believe the advantage with software undervolting is that if you're trying to undervolt too far and the CPU crashes, you don't need to mess around resetting using the CMOS battery - just reboot and start again.

 

[Vadi]

My Gigabyte Nforce550 still allows Cool&Quiet while undervolting and overclocking.

 

[Blazkowicz]

I use rmclock in XP and it works great. Have it at 0.85V for idle and 1.17V for full speed, with another frequency/volt step in between; it's set to go up one step when 80% CPU is used. So most video playback stays at lowest CPU speed, but more demanding (such as SD H264) kicks in the medium stage.

it's a 65nm sempron with stock voltage of 1.25V.
I have a nforce 520 btw. I have a +25% overclock with the same voltage and multiplier settings (can't undervolt more with no o/c, but can o/c with that same undervolt. do I have a bad undervolter?). But for now it's not o/c as I don't really need that CPU power

so you can leave the o/c to the BIOS and underclock/volt to rmclock.