3 days with no issues so far since removing Core Temp RC6, changing BIOS to F7 and upping GPU power by 20%. If I still haven't had any issues after a week I think I'll try overclocking again, the freezing at start-up was making it seem unstable before so hopefully I'll be able to get it stable at 4.5 GHz next week.
Thanks again for the suggestions V_R and wazza300 .
Thanks again for the suggestions V_R and wazza300 .