Your motherboard can't handle such godly video cards . Let alone using it to the full potential.

Having said that, I can't even run WoW and mozilla firefox without hardlocking at times.

GW, F.E.A.R., and GITS in VLC simultaneously :P Admittedly, FEAR wasn't on full settings, buuuuut that's 'cuz it tends to crash DirectX.

could be heat..

If your Graphics Card is not getting cooled well enough your system might lock this way after enough time to warm it up.. especially now that our weather is warmer. Does it lock like this on any other app? If not I would bet its a heat issue. Your card will heat up more under the constant strain of 3d gaming.

Dawn