Please figure this out

Hello all What can be the possible hardware problems when PC turns off Automatically? There are no Viruses and that i am sure Help Please ! Thankyou

Lots of reasons, but without knowing anything about the computer, or any specifics about the shutdowns, it is not possible to be specific. When did the problem start? Does it happen during boot, or only after hours of hard use? When doing anything, or only when you surf the Internet, listen to music, nothing but the desktop, using Word, etc. Reasons? Heat. Failing or stressed PSU. Failing RAM, Failing motherboard and/or leaky capacitors. Failing graphics.

Shutdown occurs automatically when i am gaming……Like if i do gaming continuously for an hour If i on it again it works fine for an hour again on gaming but after that it again shuts down This problem does not occur when i am not gaming ! Specs are: 2.2Ghz Dual core Intel celeron processor… 1 GB Ram…. 80GB HDisk 256MB Graphics Card

Well, gaming is just about the most demanding task we can ask of a computer, and since it only happens after you have been playing for some time, it still points to heat.
I would keep an eye on your temperatures, particularly, the CPU temps. Your motherboard utilities disk should have a monitoring program (or check for a more recent version on your motherboard or PC maker's website). If none, I recommend CoreTemp for newer Intel and AMD64 CPUs, or RealTemp for Intels. SpeedFan is a great and popular alternative, or you can try Motherboard Monitor. Unfortunately, I have found that these programs often have problems properly identifying and labeling the sensor they are reading. The temperatures shown are as accurate as the inexpensive, low-tech sensors will allow, but it may say System Fan instead of CPU Fan. Fortunately, the programs do allow you to edit the labels, so I use Everest to verify the temperatures (as it is able to put sensor to label correctly), then edit the label in the monitoring program. In Everest, look under Computer > Sensor, then wait a couple seconds for the readings to appear. Unfortunately, Everest does not minimize to the system tray to show real-time temperatures, otherwise, you could use Everest instead of the others

Inspect the interior for dust. Make sure your wires are routed to minimize impacting front to back flow. If you have any flat ribbon cables for older EIDE or floppy drives, replace them with round cables. Consider blasting a desk fan in to the open side of the case to see if that helps.

Thanks for the information…..let me take some steps keeping in mind this post! i'll let you know if things get better