My Computer is freezing now and then maybe once a week, fully locked up - need to reboot, pressing caps lock does not change indicator light on key board, I am told this is called hard hang.

I could be doing a range of tasks when it happens, ie watching youtube videos, closing an application, but doing the same task again after reboot will not cause a hang, benching with intel burn or 3dmark11 is stable as a rock. 
I left computer on over night, and noticed, a recovered from unexpected error screen in the morning, checked the error log, but just a basic Kernel Power message with no details.


Power supply is decent - corsair HX-1000.

rest of machine is
i7 950
X58-UD7
3x2gb ddr3
ocz ssd
3 hdds
Optical drive
6 fans
HD 6950
all at stock, except flashed 6950 with 6970 bios.

I also get more frequent loud popping noises from my speakers (5.1 logitec), even when the computer is turned off, so I'm thinking could this be a power spike issue.
I have got a surge device on the wall but its only a small one. 


Do I need to get a decent UPS or better surge protector , any suggestions / comments?

Thank you