I need Reddit’s help

Quick specs drop

CPU: 1950 Threadripper Cooler: be quiet (air cooled) ram (8x8GB): ripjaw v series Gpu: msi Radeon 6600 8gb Psu: BFG 1050w Motherboard: ASRock fatal1ty

The pc ran fine when it was first built, but recently I took 4 of the exact same ram and put it in from my old pc and now it won’t boot. I’ve tried clearing any cashes I can but I can’t even get the pc to stay on for half a second so there’s no way to get into the bios. Bought a new cmos cause clearing it didn’t work, and I have it back down to 4 slots of ram all in the correct positions and it still won’t start. LEDS turn on and it flashes red and blue when it’s plugged in and the PSU is on, but as soon as I press power on the case or motherboard it starts and everything turns on then immediately everything shuts down, with a tiny flash of the LEDS every time I press the power. I just disassembled it and cleaned everything and even put new thermal compound on my cpu but it’s the same issue and I feel like I’m running my head into a wall. Any suggestions would be greatly appreciated.