Cool CPU Software

JEN · Post by **JEN** » Sun Jun 08, 2003 6:11 am

Does anyone know of any CPUIDLE (CPU Cooling) software other than CPUIDLE and VCool. I think CPUIDLE is OK but its only for 30 days and don't think $30 is worth 3C drop in CPU temp.

Any suggestions ?

JEN · Post by **JEN** » Sun Jun 08, 2003 8:06 am

I did for a little while but the temperatures were running too high!

This is why I feel the need to use the idle time to cool the CPU instead of heat it further

Anyway, I am in search of a software program which will use the idle time to cool the CPU, which can be added to windows 2000 as a service. So it works even if no one has logged in.

Thanks for any help!

DryFire · Post by **DryFire** » Sun Jun 08, 2003 8:22 am

if i'm not istaken windows 2000 and up do that automatically.

Kostik · Post by **Kostik** » Sun Jun 08, 2003 12:38 pm

I can't help but wonder how an XP1900+ w/ an SLK-800 and L1A can run hot (assuming it's a thoroughbred), but anyway :

CPUCool is a shareware program that does basically the same thing other cooling programs do, but claims to do it better. I use it to monitor my temps (it displays graphs), and I've tested the cooling function, it works ok (-15°c to -20°c with athlon optimizations, which is what I get with other cooling programs like Cpuidle). When you enable CPUCool's cooling function, it installs a little resident program that cools the cpu even if CPUCool is not started. I don't know if this program is installed as a service, and therefore I cannot say for sure if it will work if noone's logged in, but it's worth testing.

Dryfire : Windows 2000 and up (and all versions of Linux) will execute the HLT instruction when idle, but cooling programs like CPUCool put AMD processors in C2 state, a state in which their voltage is lowered (I think) and they run *much* cooler. Cooling via HLT doesn't work as well.

I have an undervolted XP1600+ Palomino with a shitty thermatake heatsink and an L1A@12v, folding 24/7. Right now i'm testing something and my case has little airflow, so my temps have gone up a bit, and the CPU runs at 54°c folding (room temp = 25°c), which is high but should still be safe. I just enabled cooling in CPUCool for a quick test, and my CPU temperature quickly droped to 37°c. The air exhausted from the PSU is also cooler (33°c instead of 40°c), and the L1A in the PSU spins slower.

I've read in another thread that CPU cooling programs could damage the voltage regulation components on the motherboard. I can't find the thread though.

Oli · Post by **Oli** » Sun Jun 08, 2003 1:58 pm

[deleted]

Jan Kivar · Post by **Jan Kivar** » Mon Jun 09, 2003 2:43 am

Kostik wrote:Dryfire : Windows 2000 and up (and all versions of Linux) will execute the HLT instruction when idle, but cooling programs like CPUCool put AMD processors in C2 state, a state in which their voltage is lowered (I think) and they run *much* cooler. Cooling via HLT doesn't work as well.

vCool and CPUCool disconnect the processor from the northbridge, allowing it to, simply put: stop. It takes a little time to start the processor (REALLY little

), but most of the time the processor is stopped, making only a small amount of heat, thus lowering the operating temperature.

The HLT command has no effect on AMD processors, You have to use the NB disconnect bit (various register bits in the northbridge) to allow the disconnect. Not all BIOSes will allow to set the disconnect bit (=it doesn't work), but at least vCool has the ability to run "idle loop" that will cool the processor. The only bad effect on the idle loop is that You lose the processor load meter in 2k/XP, as it will show 100% use all the time (in Task Manager that is). There are some other options in vCool that will cool and "not make the processor usage go to 100%", but the loop works on all AMD platforms I've tried.

I don't know whether the idling does any harm to the processor/motherboard. The newest BIOS for my MSI KT3 Ultra-ARU adds an option enable/disable the NB disconnect bit. My 12V rail goes up and down a bit, depending on the load (MBM: 12.14V to 12.28, it raises as CPU goes 100%), and it can be heard on the fans too, as they spin up by 50 RPMs.

Cheers,

Jan

BillyBuerger · Post by **BillyBuerger** » Mon Jun 09, 2003 6:02 am

I use CPUCool myself. And yes it does create a service so cooling works whether you're logged in or not. I don't use the cooling feature anymore as I am folding now when I do have my PC running (I don't leave it on 24/7 usually) and plus I don't really see the need for it. But along with cooling, CPUCool does display a pretty nice graph of your temps and it's only $13.

Harry Azol · Post by **Harry Azol** » Mon Jun 09, 2003 8:06 am

Kostik wrote: I've read in another thread that CPU cooling programs could damage the voltage regulation components on the motherboard. I can't find the thread though.

I've also read about that, in fact I remember reading something about how some motherboards had stability problems because the power usage would fluctuate so much that it was putting too much strain on hte voltage regulator, so the motherboard manufacturer released a bios update which disabled the HLT instructions (is that possible?) to increase stability

Ex22 · Post by **Ex22** » Mon Jun 09, 2003 10:10 am

So the way these software prog work is by undervolting the CPU (AMD)?
Doesn't that effect the speed of the processor? I was under the assumption that one of the ways to OC your chop is to over-clock it. And what happens if you do have the voltage upped.

Kostik · Post by **Kostik** » Mon Jun 09, 2003 11:19 am

They work by disconnecting the Athlon from the FSB when it's idle. This doesn't affect the performance, and you should not notice it, as it happens only when the processor is not in use. According to someone on this forum this lowers the voltage the MB feeds the CPU, and thus could damage the voltage regulation components as you switch from low voltage to normal voltage several times per second.

Harry Azol : there's no way one can "disable" an instruction, but not every motherboard will let the chip go into power saving mode when idle.

Jan Kivar : I just made a quick test, and my CPU runs 0.5°c lower when running an HLT loop than when running a NOP loop. So I wouldn't say that the HLT command has no effect on AMD processors, but that it has very, very little effect and nobody cares but me

.

Anyway, you haven't successfully silenced your computer until it can fold silently and 24/7 without overheating.

Jan Kivar · Post by **Jan Kivar** » Wed Jun 11, 2003 9:27 pm

Kostik wrote:They work by disconnecting the Athlon from the FSB when it's idle. This doesn't affect the performance, and you should not notice it, as it happens only when the processor is not in use. According to someone on this forum this lowers the voltage the MB feeds the CPU, and thus could damage the voltage regulation components as you switch from low voltage to normal voltage several times per second.

AFAIK it doesn't lower the voltage. Modern processors will draw massive amounts of current (say 5-15A, depending on which rail the VRM uses). Big current fluctuations will make the PSU fluctuate voltages, as the load changes dramatically. Some rails will go up, some down. This stresses the VRM.

AMD processors will honor the HLT command, but the effect is minimal, as the CPU is still connected to the bus. Even setting the "NB disconnect bit" will not stop the CPU, if the CPU is just in HLT state. You will need to set the processor to STPGNT state, by changing/reading a register from southbridge (actually, this is done by the idle process in 2k/XP/*ix). After this the "NB disconnect bit" works, and the CPU disconnects from the bus and goes automatically to SLEEP state (as it was in STPGNT state at the time). AFAIK Intel-processor-based NBs have the "NB disconnect bit" on by default, but one must set it for AMD (either from BIOS, if possible, or with software).

Kostik wrote:Jan Kivar : I just made a quick test, and my CPU runs 0.5°c lower when running an HLT loop than when running a NOP loop.

BTW, how did You measure the .5°C change?

Cheers,

Jan

Kostik · Post by **Kostik** » Wed Jun 11, 2003 10:50 pm

I found the thread : http://forums.silentpcreview.com/viewtopic.php?t=4441, read the message by Dukla2000, he says it puts stress on the VCore regulation circuits.

I agree with you, in my experience the voltages from the PSU fluctuate when using these programs.

My Abit KX7 reads the temperatures in increments of 0.5°c. I don't know if the readings are accurate, but I repeated the process twice and got the same 0.5°c difference.

Td_nw · Post by **Td_nw** » Wed Jun 11, 2003 11:08 pm

link page with lots of software cooling This page has lots of other links on it. I am not sure about the rest of the webpages affiliated with this link page

, but the links are good. Missing a link to Vcool though.

jojo4u · Post by **jojo4u** » Wed Jun 11, 2003 11:53 pm

Jan Kivar wrote: You will need to set the processor to STPGNT state, by changing/reading a register from southbridge (actually, this is done by the idle process in 2k/XP/*ix). After this the "NB disconnect bit" works, and the CPU disconnects from the bus and goes automatically to SLEEP state (as it was in STPGNT state at the time).

Modern VIA chipsets since the kt266 also disconnect the bus if the coolbit in the northbridge is set. Only older boards need the register to be set in the southbridge.

Jan Kivar · Post by **Jan Kivar** » Thu Jun 12, 2003 2:16 am

jojo4u wrote:
Jan Kivar wrote: You will need to set the processor to STPGNT state, by changing/reading a register from southbridge (actually, this is done by the idle process in 2k/XP/*ix). After this the "NB disconnect bit" works, and the CPU disconnects from the bus and goes automatically to SLEEP state (as it was in STPGNT state at the time).
Modern VIA chipsets since the kt266 also disconnect the bus if the coolbit in the northbridge is set. Only older boards need the register to be set in the southbridge.

My KT333-based board (MSI KT3 Ultra-ARU) didn't work with just the "NB cool bit", I needed to run the idle loop (which sets the STPGNT bit) in vCool to make it work. With the newer versions of vCool, I just needed to enable "HLT detect" in vCool to make it work. With the newest BIOS, there is an option "CPU Halt Command Detection", and thus works even without the "HLT detect", so now I only need to enable the cool bit with vCool. (I haven't tested whether it would work even without vCool. If I toggle the cool bit off, or shutdown vCool, temps go up, so it seems that the OS idle process does not cool by itself. I should really try to remove vCool to see if it works without it.)

Cheers,

Jan

v3n · Post by **v3n** » Sun Feb 22, 2004 4:15 am

wow i just tried cpucool and my idle cpu temp went from 45 down to 33