System was running 100% for 7 weeks, zero issues. Suddenly wouldn't boot one day, just a blank screen. The CPU and RAM diagnostic LED ok but the green "boot" LED stays lit. Reseated everything, updated to latest BIOS via usb flashback, cleared CMOS, no change.

While it was powered off I unplugged the displayport cable, powered it on, quickly replugged the displayport cable and that worked. No eventlog issues, all game benchmarks and stress tests reported same results as before. Tested some more and veriifed it won't boot without this unplug/replug workaround. I found some posts about DP pin 20 boot issues but I'm using a cablematters DP without pin 20 so I doubt that's related as I've been using the same cable/monitor for over a year with zero prior issues. Any ideas, this is some weird stuff!

9800x3d

Asrock B850M Pro A

Vengeance 2x16 6000 CL30

4080 FE