fan noise...

[KLiK]

usually I would notice it, but the last time I was working on battery, I noticed fan noise...since then I've done some testing, here are results:

when I disconnect power supply, a fan starts building speed...also a CPU cools down, 'cause I'm doing BOINC calcs while hooked on power supply...and the fan starts making noise...I think it goes to "top speed" of rpm...


only thing I changed is the BIOS, with the latest one 2.26 version...

can someone please help me? my fan is OK when revving on normal speed...