Oh dear. Strange thing is. The computer freezes and the screen will stay as it is. For example last night I left it on to download updates. Woke up to see the time stuck at 1:43am. The hdd light on my case goes off too...
It appears to me that it is hardware (cpu) related. I have taken it as the cpu is unlocked again to an x4 but at stock speeds. probably one of the cores is falling over as the gigabyte 990fxa seems not to support unlocking cores as well as the 700/800 series motherboards did.
Try it back at x2 then try for an x3 using one of the two locked cores. Only then go for an overclock.
I would do all the software installation, update with the x2 cpu.
Did you upgrade the mobo to later upgrade the cpu or for another reason?