How to downgrade bios

SchneiderEnt New Member Posts: 1

The first twenty or so boards received have UPC1BM0X drivers and I was able to use the bios update to put the 32bit bios on. The last unit received has UPC1D11, when I try to put the old Bios on 32 or 64 bit I get: " 4 - Error: ROM file ROMID is not compatible with existing BIOS ROMID." How do I downgrade or what other options do I have for being able to install a 32bit OS
Thank you for you thoughts