Returned from work, turn on my PC and after facbooking for about 20 minutes, my system shut down without any last word. I tried turning it on, it displayed the mother board info (The first thing shown while a system start) and nothing more. I removed the hard disk a tried using it in a different PC..it works..so the problem lies in either the RAM, Graphic card (Nvidia) or the mother board..please suggest me to fix this without spending any bucks..