Jay Paroline

I don’t know how it happened, but for the longest time SpeedStep has not been working on my home machine.
Intel’s utilities said it was enabled, but Windows XP was keeping it running full-throttle at all times. I did some searching before and could never find anything helpful. The only advice I saw all over the place was to make sure that your power profile in Control Panel | Power Options is set to anything other than Home Office/Desk. I set mine to Portable/Laptop and the CPU would just not throttle down. Just for kicks I went through all of the power options and none of them would make the CPU throttle. I checked the BIOS, everything was how it should be.

For a while I blamed the BIOS, thinking that even though I had it enabled in the BIOS something was getting messed up at that level. Today I updated my BIOS and installed a new CPU (3.0GHz, 6MB cache C2D FTW), and it was still not SpeedStepping when it should have. So I did some more digging and found this page all about Intel SpeedStep.

There’s an explanation about using powercfg.exe from the command line to check and modify your power profile settings, so I dove in:

C:\Documents and Settings\Jay>powercfg /query

Field Description Value
----------------- -----
Name Portable/Laptop
Numerical ID 1
Turn off monitor (AC) After 20 mins
Turn off monitor (DC) After 5 mins
Turn off hard disks (AC) After 15 mins
Turn off hard disks (DC) After 10 mins
System standby (AC) Never
System standby (DC) After 5 mins
System hibernates (AC) Never
System hibernates (DC) Never
Processor Throttle (AC) CONSTANT
Processor Throttle (DC) CONSTANT

According to that site, CONSTANT means “CPU(s) run in lowest performance state.” Yikes, that’s certainly not what I want it to do all the time! But it’s also certainly not what it’s actually doing, either. Supposedly Intel calls Microsoft’s CONSTANT mode “Lowest Frequency Mode” — no mention of SpeedStep there. Hmm. Looks like Adaptive means SpeedStep in Intel lingo.

A little more reading and it becomes clear that if I want to try out Adaptive I just have to run the following:
C:\Documents and Settings\Jay>powercfg /change Portable/Laptop /processor-throttle-ac ADAPTIVE
As soon as I ran that I checked my CPU speed and what do you know, it’s sitting at 1.98GHz when idle. Beautiful!

Well I’m sure I’m not the only one who has had this problem, I wish I knew what caused it but at least I have a solution. My Google-fu is pretty lousy so someone else may have even detailed this solution already, but hopefully this will help others who also suck at the Google.