CPU's and power saving mode

[perdomot]

I have a Phenom X3 that runs @ 2.3Ghz normally and 1150Mhz when C&Q is used. I know it kicks back up to then normal speed when doing things like encoding video but when it stays in low gear for stuff like websurfing, downloading torrents or virus scans, how big of an impact does it have on the system to run at the lower speed? Never seen a comparison chart of how a chip functions at normal speed as opposed to when in power saving mode.

 

[nerp]

I really can't tell the difference if I disable it and re-enable it and do normal things. It's simply not detectable for me.

I've seen some benchies that tack on a few extra seconds during a long encode process or something, but nothing too substantial.

 

[seemingly random]

It decrease cpu voltage also. This requires less power which generates less heat which requires less cooling. One pc I have uses 93 watts without CnQ and 75w with CnQ at idle. Video cards have a similar feature in that they draw much less power when in 2d mode (web surfing, etc) than in 3d mode (gaming, etc).

The biggest power saver is to enable s3 mode so that the pc will go to sleep (2-7w) after it is has been inactive for some amount of time.

 

[perdomot]

I like the voltage decrease as this will help save some money and reduce heat. What worries me is any possible compromises with doing things that don't bump up the system speed. For example, copying vid files from one hdd to another.

 

[seemingly random]

Originally posted by: perdomot
I like the voltage decrease as this will help save some money and reduce heat. What worries me is any possible compromises with doing things that don't bump up the system speed. For example, copying vid files from one hdd to another.

There is very little overhead switching from one state to another (which occurs automagically). Get speedfan and watch things - it should be "run as administrator" in vista. It will become evident what's going on.

Also, get a power usage meter. A kill-a-watt can be had for <$20 online. It goes between the wall outlet and the pc power supply. It can be also used to measure how much power your refrigerator, etc is using.

 

[AleleVanuatu]

Get a kill-a-watt or go home. You're totally wasting your time unless you can see the actual power usage change!

This is a big reason I love the 38xx line of ATI's gfx cards. Goddamn low-power at idle! Best evar!

Right now, I'm using 73W (my power-usage meter is plugged in!). This is on a Celeron 1200 @ 2.8 GHz, 2GB DDR2, 3850/512MB, 750GB samsung, 500gb hitachi, dvdrw, 400W FSP.

Think about it. 73W at idle.

Oh and I never turn on power-saving, can't be bothered to re-test the system (24h orthos, 24h dft, 24h memtest) -- and it will be hard to re-test the system because voltage and clock-speed will be dynamic. Could lead to instabilities, so fuck it. 73W ain't bad at all.

 

[degibson]

Speedstep and similar CPU throttling techniques affect CPU frequency and CPU voltage. Operations that are bound by I/O anyway, like torrents, virus scans, and most websurfing, won't be affected. CPU-intensive operations, like games, benchmarking, video encode/decode, would be affected and therefore should bring the processor up to full throttle.

 

[perdomot]

That's what I was hoping for degibson. Thanks for the info.