Crash/Freze with loud buzzing (from headphones)

Not sure if this is the right section to post this, but oh well. I've been playing planetside 2 beta recently, and every so often my game freezes and the speakers emit a high pitch buzzing sound. I have to restart my computer to stop it. I've done alot of research and the only answers i can find are PSU is dying/faulty, or memory is going bad. I just ran a full memtest on all my ram and I came back with 0 errors, and I literally have a brand new PSU I put in after this happened to test it and it happened. I had my CPU and GPU overclocked, and first I thought it was a bad GPU clock, but I'm getting it at stock settings for CPU and GPU also. I'm lost here. Any input would be helpful.

System Specs:

i7 930 @ 2.8ghz
875W PSU
12 Gigs of DDR3 1333
Radeon 7950 3GB 800/1200
Windows 7 Home Premium 64-bit

blah blah. (If you need more let me know)

Thanks again.