I recently underwent a near complete system overhaul, I got a new CPU, GPU and PSU, but as soon I tried to play any demanding game on it, the system would outright just shutdown. The first thing that I noticed when I installed the new CPU, the Ryzen 5 5600X, the system would post just fine, but a second after it started loading into windows it would just shut off, so I thought, hmm, maybe it's just the garbage motherboard that I have, suddenly not liking the RAM speeds after the BIOS update (3000MHz, the mobo is rated for 3200(I told you it was garbage)), so I set the clock speeds to the next best thing, 2933MHz, and lo and behold everything worked just fine. Then I installed the new GPU, the RX 6800 XT. Still worked fine. But when I installed the drivers for it, it would crash the same way as it did before when booting into windows. I started lowering memory speeds again, down to 2800MHz with no luck, at which point I gave up and set it to the default 2133MHz and then it started working again. I could stress test it, even play some decently demanding games for a bit like rust and subnautica at max settings (I did so for at most 10 minutes), but when I tried to do something actually demanding, like playing alyx or warzone, it would shut off every time pretty much as soon as something heavy started loading.
To sum up the troubleshooting that I did I:
Stress tested the CPU for 20 minutes with CPU-Z, everything was fine
Stress tested the GPU for 20 minutes with MSI Kombustor and Heaven Benchmark, everything was fine
Stress tested the GPU and CPU at the same time for more than 20 minutes, everything still fine
Swapped the GPU to my old GTX 1650 Super, still crashing in games
Tried each ram stick one by one, slot by slot, still crashing, though I could boot into windows at it's rated speed of 3000MHz
Stress tested the RAM with both sticks installed with Sandra, instant crash, every time
Checked for bent CPU pins, there were none, I quadruple checked
Tried reseating, and repasting the CPU, still crashing
Swapped the CPU to my old Ryzen 5 2600... no more crashing, could use the full speed of my RAM and everything, completed the Sandra memory benchmark just fine, before writing this I was even able to use up all the battery of my quest 2 playing alyx at max settings 120Hz, zero issues no stuttering or nothing.
So the question remains, is the CPU or the Motherboard at fault, because I've ruled out pretty much everything else. I personally initially thought it was the motherboard because of how cheap and garbage it is (who wouldn't), but after the CPU swap I don't know what to think anymore. I've been getting mixed answers about this issue so I came here to hopefully get a second opinion and who knows, maybe a fix. I'm currently planning to send back the new CPU for RMA, before I go out and potentially waste at least 100 euro buying a motherboard.
That's all, thanks for reading
FULL SPECS:
Current CPU - Ryzen 5 2600
New CPU - Ryzen 5 5600X
Current GPU - RX 6800 XT
Old GPU - Zotac GTX 1650 Super
RAM - 2x8GB Corsair Vengeance LPX CL15 3000MHz
Motherboard - ASRock B450M-HDV R4.0 (BIOS Version 4.90)
PSU - Corsair RM1000e