POST cycling?

[Azaqa1]

A few days ago my PC starting restarting itself with no warning. After quite a bit of troubleshooting I figured the most likely cause was just a failing power supply since it was about 5 years old, so I got a new one. After plugging everything in, it pretty much POST cycles infinitely. It will go through all the debug leds, sometimes it will let me into bios and rarely it will even boot. During all this I've: replaced CMOS battery, unplugged HDD (not boot drive, boot drive is NVME), flashed bios, erased boot drive with asus secure erase in bios and clean installed windows (upon finishing installation windows did its normal reboot to complete installation, but then it started POST cycling again and windows wont come up). Prior to this the PC was working perfectly for over a year which leads me to be confident it's not any problem related to RAM seating, CPU seating, GPU seating etc

 

Any ideas on how to fix this?

 

Specs:

 

Motherboard: ASUS ROG Strix B650E-F gaming wifi

CPU: AMD R5 7600x

GPU: ASUS RTX 3070

RAM: 2x 16gb gskill trident Z rgb (6400 mhz i believe, currently running at default 4800mhz)

SSD: samsung 970 evo nvme 500gb

Second SSD: WD black 2tb nvme (not boot drive, currently empty)

PSU: thermaltake toughpower sfx 850W platinum rated

[Sawa Takahashi]

Basic troubleshooting. Try booting with only CPU, RAM, motherboard and PSU (plug your monitor into motherboard). If computer does not boot into BIOS, there is a faulty component. Try using only 1 stick of RAM and switch from slot to slot.

Try using your CPU into another computer or another CPU in your computer. If nothing works, it is the PSU or the motherboard. Try another PSU. And then, only the motherboard is left.

Hope that helps.