I've been working on this for a while now, but haven't found any reference about the problem or to a solution...

I have ACPI working on my laptop (HP Pavilion). It monitors temperature, battery level, it sees when I plug in my AC and when the battery is recharging or when it's full.

So far so good.

The problem is, that when I use DC, I have a low volume but high pitched noise(very hard to describe, it's not really very audible but still) whenever my CPU is active (or that's what I gather from it, could be something else too)... When I plug in AC, the noise is gone.

Has anybody got an idea about it?

it's definitely ACPI, because when I use acpi=off it doesn't make any noise.

has anybody got even the slightest idea what it is, and what I might be able to do about it?

Thanks

Hmm
Sounds quite similar to the experience I had yesterday. I just compiled a 2.6.0-test6 kernel with ACPI on severn-beta3. Whenever I was running on battery my CD drive was getting read though there was no Cd in it and this gave me an odd sound. Do check if this is the case. I dunno how to fix this though

it's not the case, but thanks for replying