My system specs
CPU: AMD Phenom 2 X4 840 3.20 GHz
Graphics: AMD Radeon HD 6770
Motherboard: ASUS M4N68T-M LE V2
PSU: Cooler Master eXtreme Power Plus 500 W
While gaming or watching a movie\video, sometime the screen starts flickering and i get vertical lines on the screen.
Sometimes the system recovers, with a message that "Display driver AMD stopped responding and has recovered". Other time i it crashes.
Is my power supply unit weak or is there another problem??
well the error messsage appeared to me when i'm overclocking my 7770, i've raise the core clock way to high and overheat my card, once i've change the settings to the default clock the error went away , i hope it helps
Your PSU should be fine. Have you tried completely uninstalling the AMD drivers (Use CCleaner to uninstall then do a registry clean to get out any entries in there). Reinstall the latest drivers. If that is still a no go, then it looks like your GPU is failing.
I don't know your location but here is one that I would go with no matter your budget.