So the thing I'm facing here is not new. I built my current pc something like 3 years ago. At first, I started with a completely different motherboard and GPU. had some problems, did the RMA on the Gigabyte board, didn't fix anything, and eventually decided on going for X570 Crosshair VIII hero.
When I first built the PC, I did consult the Mobo QVL for the ram, but once I decided to make a switch, it kinda jumped my mind. The thing is, the old G.Skill Trident Z Neo RAM (3600 CL16 2x8GB) I was using on my old mobo was not in the Crosshair VIII Hero QVL and every time I tried to apply the DOCP profile, I'd get the completely random shutdowns followed by a restart. At that point, once I pinpointed that the DOPC was causing it, I kinda left my RAM running at 2133 (base clock) until I got enough money to try and buy another kit of QVL-verified memory.
Years passed and I now bought a QVL guaranteed memory kit of the same model G.skill memory, but this time 3600MHz CL16 4x8GB. After multiple times of failed boots, I finally started off with a single stick, got that stabilized, then moved on to two and finally 4. Everything ran more than fine, and since I applied the DOCP profile, the performance of the system went crazy well. I ran multiple game benchmarks, even those pushing the system to the limit. Perfectly well and performing better than ever.
A day passed and I started getting these random shutdowns. Completely identical to those before. So it seems the problem with "incompatible" RAMs kinda fell off a cliff.
Now the funny thing with this situation, is that the shutdowns are actually random. I would run these really both CPU and GPU intensive benchmarks actually pushing the system to its limits and everything would run just fine. Even today I had a full play session of Destiny 2 of something like 2 hours and the system ran as well as ever. It would take another half an hour of me just browsing the web and the system just died and instantly restart. Even the night of the same day, I would play Among Us (a really non-demanding title) for almost an hour with my friends, and the system would just go down out of nowhere. No spikes in the temperature of the CPU, and no other anomalies. just a shutdown.
And I must stress enough that everything runs perfectly if I disable the DOCP and lose like a third of my RAM performance.
So a peculiar thing i have with my system is that I use a Cablemod vertical GPU mount which includes a Gen3 PCIE riser cable. The GPU I use is Gigabyte 3080 Vision OC 10GB. I had some other errors because of this combo, but the solution of just changing the first x16 PCIE slot to GEN3 in bios worked wonders and that was solved pretty fast. As I said, the system worked flawlessly in the earlier configuration which only had the ram running without a DOCP profile, which meant it was running at only 2133MHz instead of its on-box 3600Mhz.
I was pretty sure the problem was the incompatibility of the earlier ram kit with the motherboard and the first day after the memory switch almost proved it. after these renewing error, I don't even know what the hell I'm supposed to do.
The system i'm running is:
X570 Crosshair VIII Hero
G.Skill F4-3600C16Q-32GTZNC (4x8GB, 3600MHz, CL16)
NZXT Kraken X63 (2x140mm)
Gigabyte RTX3080 Vision OC 10GB
Corsair CX 750 PSU
WD Black nvme SSD and HDD
P.S. I do use CableMod power cable extensions and I'm aware that using both power cable extensions and PCIE risers adds more points of failure, but I had the same results doing everything without the extensions and having the GPU seated straight into the mobo. Didn't change a thing. Same restarts regardless.