Possibly bad A7V?

[mrhostility]

For some unknown reason, all the fan sockets on my A7V have totally stopped working. After I put some new Artic Silver II thermal compound on my processor and reattached the heatsink and plugged it into the motherboard, the fan on the heatsink stopped spinning. I tried plugging the heatsink into every fan socket on the motherboard to no avail. I tried using an old heatsink fan which I was sure worked, and changing the power supply. After both of those failed, I removed everything from the case except the motherboard and power supply. I discovered the motherboard was making a loud buzzing noise from somewhere near the processor socket, and that there was still no power being supplied to the fan sockets. Everything else on the motherboard appears to function ok. It boots into Windows and goes for about 4 minutes before the temperature rises to 55 degrees C and I have to shut it off. If you could offer any explanation at all as to why this is happening, I would be greatly appreciative.