Well.. Just realized that the fan in Graphics Card is not working... :o
Finally found out the problem!! The Graphics card temperature is over 100'C... :/
Yes, that should do it.
I dunno why the GPU fan isnt working... Is it because i am using a motherboard which has 24 pin ATX Power connection port with a 20 pin power supply? Can this be the reason?
Yes, It is possible also it could be a faulty fan/fan connector/VGA
If you use your computer mostly for games then consider upgrading your power supply to at least 24pin one.