At the moment I have my 6700k clocked at 4.5ghz @1.345 v
I have been trying to stress test the clock, and using Aidax64 Extreme, my core temperatures almost instantly hit 80°C and I stop the test. I have a hyperion H7 cooler, and really can't fathom the problem. Any advice or suggestions would be awesome.
Why did you stop the test? Your processor's Tcontrol temperature is typically in the low to mid 80's and cooling solutions are supposed to keep the temperature at or below this threshold. This is, by definition, not hot. The processor could run at its Tcontrol temperature constantly, for its entire warranted lifetime, and it (still) would not suffer any thermal-related degradation.
If you want to know what your (desktop) processor's Tcontrol temperature is, read the IA32 Temperature Target MSR (address 0x01A2). Bits 16-23 specify the processor's Maximum Junction Temperature (Tjmax) and bits 8-15 specify the Tcontrol offset. Subtract the Tcontrol offset from the Tjmax value to get the Tcontrol temperature.
You can read MSRs using tools like RWEverything.
I will be perfectly honest I have no idea how to read/access the MSR. I'm using Win 10, HWMonitor to monitor temperatures, CPU-Z to monitor clock and vcore, and those were the values I recieved.