Hi, sorry for not posting. I thought Id leave it running for a few days and.... no blue screens for the last 48 hours or so!
So, I did all of the above prior to installing the new psu and still the problem remained (It let me do the chkdsk and BSOD'd later on)
When my new PSU finally arrived we installed it and initially had some boot errors, so after some tinkering and resetting the BIOS using the little bridge thing on the motherboard (technical terms, I know) we got into Windows. We ran 3D Mark successfully but shortly after it BSOD. As a final effort my friend went into BIOS to check power settings. The MOBO was set to several weird power saving modes which seemed completely unnecessary (which ones exactly Im unsure as Id left...