Strange sound when CPU under load

[krma-thkpds]

Does any of you hear a sound when CPU is under load and speed-step forces it to run on higher frequency? (800MHz+)

Cause I here here it, but only when on battery power. If a switch to AC it stops. Any explanation would be appreciated.

EDIT: Or maybe the sound comes from the fan?

[pphilipko]

Hmmm...my thinkpad doesn't do that. It doesn't seem normal..that's for sure.

[krma-thkpds]

I just downloaded Centrino Hardware Control and it enabled custom dynamic switching. The sound stopped. Hope it will stay like this.