computer restarting

[brute]

my computer keeps restarting itself does anybody have any idea why thanks

[Timm]

Common causes of this are heat (have you looked inside and cleared out all the fluff, including cleaning the fans?), a failing power supply or maybe incorrectly seated memory chips.

If you've done this, then you need to do some investigation.
Try and make a note of how long the PC is in use before it shuts down, whether it shuts down when using a particular program etc .

If it is connected to the net, do you have updated anti-virus software running?

There are a number of things it could be so you need to try and supply as much detail as possible.

[evenstar]

Hi brute. My pc kept doing this, I put in a new cpu fan and its never done it since.