If you get it into bios look around for something like pc health post here your cpu temp and the voltages listed for +3.3, +5 and +12
Gigabyte has several versions of that board including bot socket 754 and 939 it would be a good idea to tell us the exact version you have in case we need your manual.
It would also be a good idea to tell us what cpu you have.
I doubt a 380 watt psu is enough for a AMD 64 processor, you may have been ok for awhile but the thing was problably in overdrive the hole time. A psu when pushed that hard for extended periods can deteriorate and lose alot of its power so I would consider a new one it may just solve your problem.
http://www.techsupportforum.com/hard...selection.html
That is a great artical by Tumbleweed that expalins alot about psu's along with some recomendations