Oh, and it is also really finicky about the keyboard connection, in ways that I am not sure I have seen before. Sometimes it boots up and beeps very loudly and repeatedly about a KB/Interface issue. Tends to go away if I plug the keyboard in directly, and skip my KVM. But it shows up inconsistently, and my other motherboards don't seem to have a problem with it (a Belkin F1D108-OSD).

The BIOS really did not like the serial mouse from my KVM (converted from PS/2 by the KVM) either, to a point where I cannot plug the serial cable from my KVM and use the BIOS effectively, and the mouse is uncontrollable

Trying different slots doesn't work either, post card suggests it is getting stuck at 97 Control to optional ROM.
Which makes sense, but also not sure about what this particular motherboard causes the Adaptec SCSI Bios to crash the computer when it tries to scan the SCSI bus if anything is on it.
It seems to skip 96 Initialize before C800 optional ROM control, which the list of AMI WinBios post codes says goes between 95 and 97, the previous code display on my POST card says 95. I am going to try to see if I can actually stress out the Mach32 card beyond just a boot, and see if it also has issues, just it works better than the SCSI card.

Maybe it's not a VLB issue but some sort of ROM shadow being broken? Some of these extension ROMs have bugs, and for example try writing to its own memory space. This does nothing with no shadow so everything works OK on some systems, but when shadowed, and without option to write protect the shadow, it fails. I've seen that happen.