High pitched squealing noise from mobo

compgenie

Honorable
Nov 18, 2012
250
0
10,790
I'm using a Gigabyte GA-MA785GM-US2H, a phenom II x2 555.
The speaker is squealing, but I'm unable to identify the problem because Gigabyte doesn't have a troubleshoot manual available. Not is the computer getting till the boot phase
If powered on, the mobo starts, then all the fans slow down briefly.
They spin back up to normal but then the beeping starts. each beep is around 2 seconds long.
This happened after my brother used some kingfisher headphones, then after unplugging them, the beeping started and now it refuses to turn on. Have tried to unplug the audio connector. Didn't work
Any help would be appreciated