Undervolting

[Tyr_7BE]

Very interesting. I'm going to play with this once I get my laptop as a fallback box.

Thanks for the pointers! Karma++ for alerting me to this!

[gorn]

Is it a powernow-k7 laptop?

I'm working on cleaning up the code and setting it so you can both control the current voltage and alter the table so that when a daemon like cpufreqd or powernowd changes the frequency the voltage is set to your prefered voltage, not the default.

I'll post the code when it works (And I could post the dirty hack in the mean time if you wanted)

[Schotty]

[quote author=gorn link=board=3;threadid=9364;start=0#msg84922 date=1087783930]
but keeping the same clock speed and cutting voltage will not give you a performance lose, however it might make your system crash.
[/quote]

To me, a crashing PC, is poor performance. Going from stable to unstable is a performance loss. The recoomended voltage is intended to be a value that will keep the data intact over the course of one cycle. However having an EET education, I also know that just because it works for one moment, doesn't mean it will operate at another instant. Transistors are not as precise as many make them out to be.

[gorn]

[quote author=Schotty link=board=3;threadid=9364;start=0#msg84929 date=1087825995]
To me, a crashing PC, is poor performance.
[/quote]

Agreed, and that's why you don't use the voltage that will cause it to crash.

Transistors are not as precise as many make them out to be.

Ahh exactly. So how can they really give 1.25v exactly when they are supposed to? They don't. So undervolting to 1.125v might actually really be only going to 1.20v because the motherboard overvolts by default. So your undervolting is really just cutting off the excess voltage. Plus no chip is the same, some can take more than others. I'm not saying undervolting doesn't require testing though, and I'm not saying it's for everyone. But all these inprecisions can be tweaked if you know what you're doing.

[CP]

I have to agree with Gorn here. My processor will let me overclock it at default voltage, so I theortically could undervolt it at default speeds.
You can get a stable undervolt, just need to stress test it. If it works fine with stress testing undervolted, then it should be able to survive every day use.