I don't really have any non-essentials - 1 HDD, 1 Graphics card, 1 DVD drive. The PSU is a pretty good quality, high amp one with minimal extra stuff and the issue appears with only minor voltage increases. It was working fine for a while before the issue too.
Thanks for the suggestion though
I kind of think it's most likely to be memory related, which seems to fit the symptoms and presentation, but I don't know enough technical details to know if i'm right. Someone with a similar experience would help but extensive searches on google found nothing the like my problem.