Custom built PC has BSOD after a year with no issues

Thanks for the detailed response, I have run drive verifier however as it says on thta guide, but my PC only lasts about 2-5 mins each time before the screen comes up with stripes across it and stops working without a hard reset.

How do I find out which driver is causing this?

Also I have taken 1 stick of RAM out and the PC seems to not do the BSOD when I don't have drive verifier running, its gone 2 days without but not sure if this is just chance.

Have you tried booting into Safe Mode? Only the most basic drivers will be loaded.