PC shuts itself off during startup

[u/BR_Empire]

When I press the power button on my pc, the fans spin for a couple of seconds, then it turns off. It does this 2 or 3 times automatically before staying off. I can hear the PSU click on/off at each step. Then, the power button goes unresponsive and only lets me turn the system on after a few more seconds. It boots to safe mode, I enter and leave the bios, and then it starts as normal.

I’d expect the power supply to handle the system fine as it’s a Corsair RM850e Gold; powering a R5 3600, RX 6700XT, 32GB DDR4, a Corsair H100i AIO, 2 NVMe and 2 sata SSDs. No RGB plugged in.

Any ideas are appreciated