GSOD while playing games

I have purchased a brand new Graphic Card. From the moment I have installed it into my PC, every time I play a game, it crashes - it does a "GSOD - Grey screen od death" - screen here: http://www.hardwarecanucks.com/wp-co...n-of-death.png

Depending on the game's performance, it crashes sometimes faster sometimes slower. It crashes ONLY during playing the game. At random times. I have tried almost anything, my old card works fine, I tried several drivers, I have the most up-to-date BIOS and DRIVERS, I did a RMA but they told me that the card is OK with no problems... I dont know what else to do - someone told me that it might be some kind of BIOS issue/failure. I also tried lowering the GPU's frequency.

Also, it is not always pure GSOD, sometimes the lines are green etc, sometimes the sound goes into LOOP.

Please help

Thanks in advance,
Karlos


-------------------------------------------------------------------------------
Model Name : GV-R785OC-2GD
--------------------------
PCB ver : not sure, maybe 3.0
Driver Ver : 12.10
-------------------------------------------------------------------------------
Motherboard Brand : GIGABYTE
Model : P55A-UD3
Operation System : Win 7 64-bit SP : 1

My GPU temp did not go over 80°C. When I play, the temp can be around 45°C and it crashes, so I dont think it is a overheating problem.

My drivers are all up to date (it is in my first post), including MOBO and other stuff. My GPU is an OC version, so I even tried to put it down, did not help. I am not overclocking anything.