Z370/Z390 motherboards could be overpriced either because of a combination of the global motherboard shortage and the fact that Z390 is most likely discontinued because of the release of Z490/Comet Lake. That's why Coffee Lake now isn't really a smart purchase.
Regardless though, overclocking with locked CPUs/chipsets has become increasingly harder with Intel, so I wouldn't necessarily find it surprising that you can't alter the clock nearly at all with a B365, despite having an unlocked chip. I'm also not aware whether MCE (multi-core enhancement) is available for B-series motherboards, as that'd be an automated option to run all cores at the single-core boost (so 4.6GHz in your case, from 4.3GHz).
What I'd suggest is trying to update the BIOS and seeing if that helps at all, or checking if you've any more options in Intel's XTU. If none of these help/work, I think you might just be stuck with tinkering with the BCLK multiplier, though go easy on it as it could cause instability not just of the CPU, but memory and even PCI-E devices.
arisreddy got a reaction from Mateyyy in Issues with 9600kf max core clock on B365 Mortar
