So I recently finished building my computer and my cpu usage kept on spiking up around 8% while running nothing other than being on the desktop. I installed some games and my computer was at 20%+ usage when playing a 2d game. When I tried a more intensive game the whole computer froze (not slowed down) and would not let me even open up task manager (the mouse will not even move). My friend has the same processor and motherboard and he gets 3% CPU usage when playing very intensive games.
I haven't, the only things I have done after building the thing is downloading 2 steam games and a desktop picture.
Very very odd, maybe you should try reapplying thermal paste & reseat the heat sink assembly. If no result, send the CPU back for it maybe defective. I would never recommend a 3930K for gaming to be honest - that CPU is for serious workstations and servers IMO, a 3570K would have been a smarter buy. Just my 2 cents.
I mean, 50% off is a good deal, but still, it's not an ideal gaming CPU really - 6 cores and 12 threads have very little to no effect on most games. Advice given, I hope the best and that your problem resolves itself - goodluck, and happy computing!