While this may only be tangentially relevant to this thread, I think it's worth adding, nonetheless.
I have had an FX-3000 motherboard for a while, and when I first received the board swapped the EPROM for an EEPROM loaded with the UMC480's corresponding MR-BIOS. I recently came across the original EPROM for this board and finally dumped it and noticed that it references an OPTi chipset! Now this is especially odd because the actual chipset is, as aforementioned, the UMC480!
Like the OP's board, this board seemingly has a BIOS that's either mismatched for the chipset and was just slapped on the board, or there's more at play here. I think it's certainly interesting to note that a supposed OPTi BIOS worked just fine in a UMC480 board.
Now I have no idea as to whether this BIOS is original to the board, but the sticker on the BIOS matches the keyboard controller and the board was sold as NOS--and seemingly was indeed in such condition, when I first received it a few years ago. The OPTi BIOS worked totally fine, except 486 support was nonexistent. 386s of all variations worked correctly.
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