Question Computer boots only once out of 10 times

Mar 1, 2021
Hello, so I built a brand new system about 3 weeks ago. My computer boots only about once every 10 times. When it boots everything is fine, I can run stress-tests, play games, it wont crash or reboot or anything. When it doesnt boots, than the fans start to spin, led goes on and otherwise no response, not even the bios boots, mouse and keyboard dont light up.

I tried unplugging and replugging RAM, tried with 1 RAM, unplugging and replugging USB-Devices and every cable, I removed CPU and reaplied thermal paste, I updated BIOS to the latest one, I reinstalled windows, I unplugged and replugged CMOS-battery, I let it overnight without unplugged form power, turning off PSU and back on multiple times. The computer sometimes boots and sometimes doesnt (mostly doesnt), and the above mentioned things dont affect if it boots or it doesnt. Sometimes it boots after a change, I think I found the solution, but then it wont boot the next time.

I used a ryzen 3100 to upgrade BIOS, I only booted up the system once with that and it functioned, then I did the CMOS-Battery reset.

Asus rog strix x570-I (Bios 3406 )
Hyperx 3200 mhz, 32g RAM (HX432C16FB3AK2&32)
Ryzen 5 5600x
Rx 6800xt
Seasonic focus sgx-80 SFX 650W
Adata XPG sx8200 - 2tb SSD
Kraken x53-CPU Cooler

Windows 10 pro

Any suggestion what the problem could be? Ty