I decided to test all core overclock at 4.7Gh again, this time to see how low I could take the voltage. Maybe it just requires lower voltage to overclock higher - less voltage, less heat
At 4.7Ghz, 1.2375V in BIOS it was stable for 5 runs of Cinebench R20.
All cores stabilised at 1.225V running R20 multi core.
Max temp 74c with a Noctura U14S
I tried one lower at 1.2250V in BIOS. All core voltage ran at 1.212V but resulted in an R20 app crash.
At 4.7Ghz, 1.2375V in BIOS it was stable for 5 runs of Cinebench R20.
All cores stabilised at 1.225V running R20 multi core.
Max temp 74c with a Noctura U14S
I tried one lower at 1.2250V in BIOS. All core voltage ran at 1.212V but resulted in an R20 app crash.