Now that I remember, I had similar problems with my rig freezing/locking on me and it turned out to be the drivers for my monitor. This may not be the same problem you are having but, perhaps, worth trying?
See if your Device Manager shows your Monitor or if all you have is a Generic P&P Monitor? if the latter, check for x64 drivers for it.
That corsair PSU seems to be a good psu but I would be weary with just because you run a lot of devices.
I have a Toughpower 600w and I can't run my Evga GTX260 + ECS 8800GT w/o hindering fps's, as soon as I take the 8800GT out, my system runs much better... seat of the pants benchmark only though.