Overclocking

Thanks to an unlocked multiplier (the "K" suffix in 12900K), overclocking is really easy. You can just adjust the multiplier freely in your motherboard BIOS or the XTU overclocking software.

I set the voltage to 1.4 V, which is about the maximum our Noctua NH-U14S can handle. Maximum stable frequency at that setting was 5.0 GHz on all cores. After switching to our 360 mm Arctic Liquid Freezer II AIO, the processor was also stable at 5.1 GHz all-core, but required 1.5 V, which the AIO could handle (the Noctua could not).

Overall, I don't think manual overclocking is worth it given the massively increased temperatures and heat output.