I'll try to put in as many details as possible to filter out most common problems.
Sometimes my computer will go into a sort of standby mode and the only way to solve it is to reset. It can sometimes happen whilst doing simple windows task but it is guaranteed to happen during a game after a few minutes.
However, if I put my computer into safe mode, this will not happen.
A few problems I've filtered out are:
Memory: I did a 16 hour memtest with no errors
Gfx Card: I've replaced the gfx card
Driver issues: I've reinstalled Windows multiple times.
Hard-Drive: I did some hard drive test thing, but I'm not sure how accurate it was.
What else could it be? and is there a way I could check without having to potentially waste my money on new parts which may not fix the issue?
Thanks for your time