My computer randomly shuts down, I checked CPU temperature, its always between 35-45C, there's no definite timing when the computer will shutdown, sometimes it shutdowns even before the boot screen comes, I'm sure its not CPU overheating problem(Applied new layer of thermal paste and temperature is always <45C) and Not OS problem also because the computer shutdowns even before it is started, I have no idea how do I troubleshoot the problem, what might be causing the problem?
Situations when the comp shut downs :
Sometimes when it is idle
It doesn't cause me any problem when playing games/playing music
This might be a memory issue. Try getting a live cd (or DVD) with memtest86+. If it comes up with errors, then it is time to change the RAM.
If errors are found and you have more than one stick of RAM, then test them all seporately. You might be able to limp along using just one stick.
Other causes could me death of the motherboard components. Do a visual check to see if there are any leeks from the capacitors or if they have rounded tops. The capacitors are the cylindrical components that can be found all over the place on motherboards and expansipn cards.
Another cause could be a bad "add on" component. Remove all unessential stuff - leaving if you can just the RAM, Hard drive, power supply and if it doesnt have a built in one, the graphics card. Unplug all external devices like printers, network cables and the like. Just leave in the mouse and keyboard. Add them again one at a time until the problem returns.
I really appreciate kudos points as a payment for solving issues :o)