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CPU Idle

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Knee-Dragger

Registered
Joined
Jul 5, 2004
Location
Oregon
Is CPU Idle all that's its cracked up to be? I mean does it really stop the CPU when inactive to keep the temps lower?

Been reading folks' XP-Mo 2600 Idle temps and mine seem really low compared.
I do have A/C in my house and its relatively cool in the house anyway.

I've ran CPU Idle for 4 days now and really like the temp I get. Then I just turned it off and the Idle temp just rose to 44c.

Just curious if any you Wizards out there know the real deal with this utility.

EDIT: Oh BTW, I'm using SpeedFan to read my Temps.

System in SIG. I think :confused:
 

JigPu

Inactive Pokémon Moderator
Joined
Jun 20, 2001
Location
Vancouver, WA
CPUIdle works by issuing "HLT" instructions to the CPU. When HLT (think "halt") is executed by the CPU, it's clock is turned off for a small amount of time. Because the clock is off, the CPU produces less heat, lowering idle temps.

Win9x doesen't use the HLT instruction when idle, but rather just does a do-nothing loop which takes up any unalocated CPU time. NT/2K/XP/Linux however use the HLT instruction (and disable the clock, instead of doing a meaningless loop), meaning that they should provide idle temps similar to what CPUIdle offers.


However, may I suggest the possibility of putting your idle time to use (instead of just executing endless HLT statements) by helping one of our forum's distributed computing teams? We have two teams, one that helps Stanford's [email protected] project (which simulates protien folding, hopefully finding a cure for various diseases) and one that helps UC Berkeley's [email protected] project (which scans data gathered from the Arecibo radio telescope for possible signs of intelligent life). You can check out each team's section of the fourm here, and here :)

JigPu
 

Sonny

Senior TIFOSI
Joined
Aug 3, 2001
Location
VARIANTE ASCARI
Knee-Dragger - The latest version of your BIOS should have this option available for you to use instead of having to use software to change the registers from within the OS. AMD asked this to be included to take care of some hot chip issues.

JigPu said:
Win9x doesen't use the HLT instruction when idle, but rather just does a do-nothing loop which takes up any unalocated CPU time. NT/2K/XP/Linux however use the HLT instruction (and disable the clock, instead of doing a meaningless loop), meaning that they should provide idle temps similar to what CPUIdle offers.

Actually the the OSs that you mentioned, not including Linux, can not by itself idle a CPU. The MoBo needs a BIOS that allows for these instructions to be accepted or it will be ignored and true idle will not be achieved.