Hi, I am having this problem for quite sometime. Mostly this happens when I browse net or play games (on loading screen only). Please help me. My configuration is: Intel Core2Duo E7200, Gigabyte G41MT-S2P, 8GB Ram, Sapphire 7750 Graphics Card, Seasonic 620W Power Supply. Thanks in advance.
You mean coloured lines or screen of death?
run pc without graphics card using onboard video to check if problem still remains.
It might be your gpu problem.
I recently bought the power supply (Not more than 2 months). It is a Seasonic S12II Bronze 620 Watts Power Supply. I think it has more than enough power for my entire system.
When it freezes, it looks similar to these: Screenshot 1, Screenshot 2.
then check your gpu temps by running gpu-z.it seems like gfx card is over heating.