Hi

My sister has this problem with her computer. sometimes it shuts down. No BSOD or anything, just like when you pull the plug. What are the main causes for this problem? Hardware or Software?

Hello and welcome to PC Help Forum.

This could be an over heating issue,due to fans/cooling failure.

When computer is on could you check fans are spinning.

The fans were spinning, and now my sister says that its not just shuting down it is restarting.

Ask her to try restarting PC and then repeatedly tap F8 for safe mode/last known good confi?

Hi-- I suspect a PSU problem here...
Go here : Download SpeedFan - Access temperature sensor in your computer

dowload and install Speedfan-- do NOT panic if you see some odd readings when it first runs-- not all sensors work with it-- and I am more concerned with voltages than temps-- I have to go right now... but I'll be back in a couple of hours

I already have Speedfan installed, was checking some temps, but what to look for?

Hi-- sorry for the delay-- work called me.

There are two things we want to look at...
Temps, of course -- could cause your symptoms
But the way your system acts, I am thinking more of Voltages

at the very bottom of the speedfan initial window--

you should see :
Vcore
+12v
3.3

and a few others-- the above are the primary ones--
What do yours say--?
If they're not there you can turn them on using "config"