I set Cinebench to only use a single core and ran the single thread benchmark, confirmed 100% utilisation on one core only but the speed sits at 3.7GHz no single core boost to 4.0 and no XFR to 4.1. Temps are around 40deg doing this single core test. Cooling is good; AIO so should be sufficient for XFR.
In fact the processor seems to sit at 3.7 on all cores all the time. Doesn't drop to base block of 3.6GHz and doesn't boost individual cores.
Motherboard settings are all set to Auto.