instability and caused by which hot part ?

not sure this is the right area but here goes.
im currently at 240 default vcore mem 5:4 lax timings in still in spec. everything seems fine . If I push it abit more to 245 witha vcore bump to 1.55 I could bench a few times but after a few mins i get program errors (quake crashed).
at 250 it hard locked on my way to windows so is there any answers as to what causes what types of crash . im guesing its the cpu since the mem is still in spec but i could be the N/B needing a little more cooling power , or even abit more vcore needed.
temps
sys 28-30
cpu 47-49 load

IC7-G has a heatsink/fan unit so it's doubtful that it is the northbridge heating up. I'm putting my money on the cpu needing more voltage.

yeah im thinking its the cpu too not too keen on putting any volts through it tbh as my temps aint exaclty icey cold.
looks like 240 is about my chips limit.