BSOD on Custom Build - STOP 0x00000124 (0x9511E01C, 0xBF800000)

I am new here so HELLO EVERYONE

I came with the question about my custom build:

Two weeks ago I was playing GTA and computer turned off. Then I had problem to turn it on but finally once it gets on I had BSOD (Please check the attachment) after every 5 minutes and decided to reinstall my system. Now when I try to install fresh system BSOD won't let me do it as every time Windows is copying the files BSOD coming on the screen. When I operate in BIOS everything is ok. Tried to restore Optimal settings in BIOS, set the DDR timings, changed DDR, reseated CPU 2 times, reseated DDR's, unplug all usb devices and second HDD, run just with one GPU in different PCI-E ports and with no luck. Don't know what to do. Change motherboard? Change CPU? Power supply died or maybe it is something little? I can add I've changed thermal compound about two weeks before that and added second GPU.

Error says it is uncorrectable hardware error and STOP: 0x00000124 (0x00000000, 0x9511E01C, 0xBF800000, 0x00000115)

I did tried that -> Stop 0x124 - what it means and what to try
My PC is always clean as new (Filters and regular cleaning by soft brush and air) Cooled in NZXT Phantom 630 case with Corsair H100i watercooling.