What are your system specs?
So everything was fine up until a few months ago? Do you remember if you added any hardware, etc. around the time the problem started?
What are the temps for your cpu/video card like?
Have you tested the rails on either or both of the psu's? If you're not sure how to, there's an excellent guide here-http://www.devhardware.com/forums/power-supply-units-98/what-s-a-multimeter-how-to-use-it-to-test-75111.html
When the game freezes/sound loops, what happens? I mean, does it force you to reboot the system or just close the game?
Have you tried running memtest (www.memtest86.com
)? I guess if you have more than one stick of ram and you've tried them all individually, you're problem's probably not there, but who knows?
Have you tried killing all non-essential applications when you run these games (turning off anti-virus, etc. programs, absolutely anything you don't absolutely need to have running)?