System reboots/crashes start of games

Please Help
At beginning of game (Crysis, COD Black Ops & Splinter cell) PC will either reboot or shutdown without warning.
Must switch off power supply to restart most times.
At all other times runs fine. Will even run Company of Heroes
Just rebuilt PC with new MB, GPU, Ram and installed Win7.
Fresh install of all games.

System build is:
ASUS P5G41T-M Intel G41 Chipset Socket 775 Motherboard
ASUS nVidia Geforce GTX460 1GB
2 Corsair 4GB DDR3 133 (PC10666 - CMX4GX3M1A1333C9)
Intel Core2 Quad CPU@ 2.40GHz
HDD 2 x 320gb
750 watt Thermaltake PSU
Windows 7 64 bit

 

This could possibly be a memory issue, and that is why only certain programs cause the crash. Try running a RAM testing program (memtest comes to mind) just to verify that your RAM is good.

 

Thanks abeki for your help.
I noticed something in the startup about shutdown for power surge?

I checked the ASUS website and there is a setting in the BIOS setup to protect the system from power surges & this is causing a lot of problems.

I located this setting and set it to off.

This is it, all fixed now. :wave