Well, here is my guess:
I doubt it's XMP related. In such case, the PC would crash and mostly stay there, required manual power-off. After such crash, the XMP would turn off by memory training itself.
750W is more than enough for 5950X and 2060X, and the Asus has "good" reviews, there are two issues:
1) Based on
https://linustechtips.com/topic/1116640-psucultists-psu-tier-list/ we can see that all generations of this PSU range, has '1' issue mentioned: Transient loads. That means that even despite fitting into overall power envelope of the PSU, spikes will crash it. And 5950X with its high turbo, and particularly large spike voltages, is the perfect unit for this. PBO shouldn't really change this since it foremost ups the total power limits, but doesn't really lead to much higher voltages.
2060S should not be the culprit. But almost all Ampere (30xx) range has also transient issues. For example 3090 has 320-350W limit by stock, but spikes can be up to 500W !. Those will crash most common PSUs.
I would try swapping the PSU first, it's almost easier than playing around with voltage curves, bios and software solutions, etc. That will just get on your nerves very quick.
On top of this, I would highly suggest against PBO, esp. with Zen3 chips. There is absolutely no point to it. You can play with so-called "PBO-2", but its benefits can be a risky trade-of with stability, as is always the case with under-volting or manual voltages in general. Although there will be plenty of people to tell you otherwise, so this is just my personal opinion on PBO2. The opinion on PBO (ver1) is almost universal by now though, don't touch.
Most reputable Tier1 PSU units I will always stand behind: Seasonic
Prime, Corsair
AXi. There are tens of Tier2 which are more than capable (Higher EVGA range, Superflower Leadex series, etc..) or, you can see how big the list is the link above. But still, I consider stability in workstation to be so paramount that I will always go for the highest PSU.
I had almost no PC crash in a decade. Though I don't count PC memory boot issues (XMP/DOCP related).