My PC just switches off?

[rigsby]

The PC 4 years old now but is perfectly satisfactory for my current needs, however it has developed an annoying habit of every day or so it just shuts down, like someone has switched it off at the mains. It only does this while it is doing something processor intensive (ish)...it will sit doing nothing for days/weeks on end and not shut down, but running say a registry clean up program or running a few programs at once and suddenly pop...it switches off.
I have replaced the power supply to no avail, any ideas??

[Howard]

Power Su... oh.

CPU fan/heatsink isn't clogged up?

[rigsby]

Not sure the cpu has a fan!! but I will take a look!

[Howard]

It will if it was built after about 1996

[harry1]

check all your plug connections to hard drives motherboard ect

[MD]

please do not cross post.

You already have a thread in the scan forums.

Matt