New Computer Crashing - Not sure if it's GPU, PSU, Motherboard. Did 5 hardware tests, still clueless

JayJames · February 7

Hi! Built a new computer, need it for work.

Context:

- New parts: i7 14700k + Maxsun Z790 + 64gb ram corsair 6000mhz + MSI MAG A850GL 850W.

- Old parts: RX590 TDP 175W (need to use old GPU, I test games). Cleaned and put new thermal paste.

Extra info: Updated bios, drivers, everything. Mobo has 2 CPU power headers, I plugged both of them in.

Extra info: CPU is not overheating (PS120SE), GPU is not overheating, memory is not overheating.

Problem:

- Computer crashes if I leave the RX590 at 100% power limit. Mouse/image freezes and I need to reboot manually.

- Stable if I leave the RX590 at 85% power limit.

- Stable if I put my old PSU (old model CX600M) even with the GPU at 115% power limit.

Tests I did (all with stock CPU/mobo, except for first):

Hypothesis:

a) New 850w PSU is optimized for PCI-E5 (16pin) so it can't "deliver" much through a 8pin (6+2) RX590.

b) Some stock config is letting the mobo pull insane amount of powers (its at default/stock).

c) Faulty 850W PSU.

d) RX590 (TDP 175W) + 14700k is "too much" for a the MSI MAG A850 850W (gold rated, tier A) - this would make no sense as the CX600M was holding the same setup fine.

e) I'm dumb and I'm missing something obvious.

Questions:

I) What should I do? I'm tweaking for 5 days and getting insane, I can't return the PSU now as I need this pc to work, I got a newborn baby and money is short.

II) Does it make "sense" that the new PSU is optimized for new cards and deliver "too little" on the old 6+2 pci-express cable GPU?

III) Does the type of "crash" with the image freezing, fans still spinning means something in particular? Or is it generic? Every error I had was 41-(63) Kernel-Power.