Asus Hd 7850 Screen Flickering

[DrDark]

Hey,
I'v started having problems running games recently.

My system is:
MOBO: Gigabyte G41M-ES2L
CPU: intel Q8200 2.33GHz
ram: 2x2GB
GPU: Asus HD 7850 V2
PSU: Mono mode ATX-550

When i use the computer normally everything is working perfectly, but when i try to launch any game the screen starts flickering for a minute or two then going black screen until i hard reset it.

i used to play games before without any problem i have no idea what happened.

Thanks in advance for any help

 

[DrDark]

im really frustrated i tried a lot of stuff...

like updating mobo driver or re-installing the GPU driver.

can you please help me solve this thing?