I am almost certain the issue is the motherboard, it's the only thing I can link between our systems, that and the fact we both got them at around the same time.
To update, I left mine unplugged for 12+ hours, turned on first time instantly, so since I reset cmos last night, I loaded gamer oc profile instead, lowered the clock to 4.4ghz across all cores (with 1.25v from oc profile) and am testing prime95 now, will leave it on longer this time to see if it locks up.
I genuinely think it's a bios related issue. Could be the battery?