Problems with my new rig.. help

[fonzthegreat]

just put together a new rig... everything in windows is fine, when i watch hd movies, no hiccups at all. But when i start to game, after about 10 seconds, the screen will get all corrupted with this weird sound coming from the speakers then the pc will restart. no BSOD nothing.. this only happens when i use 3d mark and masseffect.. weird when i play C&C3.. everything plays normally.. i didnt overclock my system.. is it a hardware or software fault? here are my specs

HEC winpower 550w

ASUS P5Q DELUXE

intel Q9400

kingston DDR2 800

PALIT SONIC 4870 1gig

2x raptors raid 0

vista ultimate 64bit

running the latest bios and catalyst drivers

any help is appreciated

 

[shortstuff_mt]

"HEC winpower 550w" - That would be your problem. HEC is not a quality PSU manufacturer. Even with a quality PSU, 550W is pushing it. Your computer runs fine until your GPU goes into 3D mode (games) and then the PSU can't deliver enough power and the system shuts down. You should look into a quality 650W PSU from Corsair, PC Power & Cooling, Antec, etc...