I'd seen the Hyper threading as Dual Core checkbox in OCCT3 (5th line down, Centre) :

It wasn't until I was running Coretemp alongside OCCT3 that I realised the significance of the 4 core 2 thread impact on benchmark loading.

You can see from the above that
CPU loading is only around 50%. In other words the cores are loaded 100% but only using 4 threads NOT 8.
Ticking the box in OCCT runs with the full 8 threads on full load:-
Impact of this is that average temps on Full 8x threads will be higher. If running with Hyper Threading unticked, your stability may not be as good as you think, as your not testing on full load, you may need extra Volts to get there.
Temperature & load Stats for the two methods are:-
Unticked x4 Threads

Ticked x8 Threads