Overclocking on the Z590 platform is pretty much the same as what we saw on Z490. You will notice, at least with the Core i9-11900K that you are not going to be able to get a whole lot more out of these chips. I decided to do all of my overclocking using the Intel Extreme Tuning Utility. Opening it up by default in Advanced Tuning we can see the break-down of ratios by active cores.
To set an all-core overclock all we have to do is adjust these values. After much testing we were able to achieve a stable overclock of 5.1 GHz (51x) with a set Vcore of 1.35V. We could easily boot the system at both 5.2 GHz and 5.3 GHz (all core), but the system was not stable.
Running the CPU stress test it passed, but our temperatures decently high, so that is something you might want to keep an eye on.