You have the best motherboard in terms of power cascade, but it's Asus so... the quality control is what it is :- ). Unfortunately. Do you have the latest bios? Chipset drivers? (it has to be installed in that order, you need the former for the latter, esp. for stable 1903/2004 Windows 10 builds).
Enermax Liqtech can be faulty even from brand new but you can only tell by monitoring temperatures. With 2990WX, and Liqtech, they should barely if ever touch above 70.
What about the memory? Is it running XMP? Definitely don't try to run it faster than 2933/CL16. Definitely not 3200-3600. Even if it works for a while.
Is that PC unstable even with default (2133) frequency?