OURFAMILY631

hi yes it is a desktop, even in safe mode it is the same. it has been playing up for ages just turning off at will so i have changed the power supply and cpu heat sink and as i was going to be changing them i thought i would get a new case so put them in as thought might be part of the problem as in power supply stopping thats why it kept shutting down. or CPU getting too hot but they havent changed a thing. had a old graphics card that was working fine so changed that no difference. then i picked up some ram yesterday cheap and when i put that in today made no difference. and also i get a small 250gb hard drive that i could have installed windows on and then just had a small drive with all the programs on and then personal stuff on my other two. still no change wont even run the windows install program stops part of the way through so now i am thinking that it is what my first thought was and that is it's the mother board. just toying weather to change it. anything else i could try before getting another motherboard.

I am having problems with my pc, as it keeps stopping, not even the caps lock is working no matter how long it is left. sometimes it boots up sometimes it stops working before windows even finishes booting up. if i get the option to repair and i run it then it runs till it also stops. i am totally at a loss as to what it could be. I have got a hard drive docking station and i can see everything on the drive when it is connected to my laptop and i have runs a virus scan on it without abnything showing up. Any help would be great