EVGA GTX 275 Overclocking Problem

Hello guys, I think I have an overclocking problem with my 3 day old PC. I overclocked my GTX 275 to 705 core / 1586 shader / 1200 mem and I started 3D Mark 06 and after loading the first test, the screen goes black for a second and 3d Mark freezes. I have to ctrl+alt+del to close the program. Same with CoD: WAW, after playing for a couple of minutes, same thing happens. Everything is fine when I have the video card on default settings though. 3D Mark 06 and Vantage runs fine and gets normal stcores and CoD runs fine as well. So when it freezes during overclock, I get a yellow icon at the task tray that says:

"Display driver nvlddmkm stopped responding and has successfully recovered."

My last video card was a X850XT and i'm fairly new to overclocking but the 275 should be able to handle that right? Any info/suggestions would be awesome. Thanks

Also.. I think i might have a problem with my Corsair power supply. It makes buzzing noises during games only. I was thinking that was the problem.

Cooler Master HAF 922
EVGA GeForce GTX 275
EVGA 141-BL-E757-TR LGA 1366 Intel X58
OCZ Gold 6GB (3 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800)
Cooler Master V8
CORSAIR CMPSU-650TX 650W ATX12V / EPS12V

hi, just to let you know that i have the xfx version of the 275 with nearly the same build as you. and also i did oc the cards to 700/1200/1470 with no problem, i doubt you are over overclocking it. the driver error wasnt good for me, i took my system back to the store and changed both the graphics cards. it would only give this error on certain games, like on bioshock i would get it before the intial loading of the game. back to the point, your card could be faulty, take it back