Just flashed the latest 2M seabios text rom onto the PDIP-8 chip that came with the motherboard.
It boots! But, it says there's some device error (this is probably because the PS/2 port is broken, I was getting an error with stock bios too), and then the cpu fans go VVVRRRRRRRR, probably like double the full speed, it's super loud, like it's gonna blow up or something. Also, neofetch says the CPU is at 0mhz, instead of 3.7Ghz.
I tried switching the cpu fan jumpers, nothing changed. Both CPUs are Opteron 4284. Motherboard is from August 2013. Should I drop another $120 on another KCMA-D8 board, or is there anything else that I can try?