So after much faffing, I'm running a -0.08v offset on the CPU, can't change BCLK at all or lose boost, regardless of other settings, but getting decent per-core of 4.355GHz and all-core 4.15GHz on the stock cooler, at reasonable temps on Ryzen Balanced power profile.
Guess I can't grumble too much at that...
So..... does overclocking not kill the precision boost thing?