While modding my Dell Optiplex 3050 to support Coffee Lake CPUs, I successfully added the required microcodes to the BIOS, and the system boots normally with a Kaby Lake CPU (I haven’t tested a Coffee Lake CPU yet, as I wanted to first ensure the BIOS supports the Coffee Lake iGPU).
However, any change to the VBIOS or GOP Driver - even a minor update (without changing VBT) - causes the system to boot into BIOS recovery mode.
Working BIOS (with updated microcodes): https://drive.google.com/file/d/156HPV9OFstC3entnMLIwGgSN7Oe-3wIs/view?usp=drive_link
Same BIOS with only GOP Driver updated from 9.0.1056 to 9.0.1080 (boots into BIOS recovery mode): https://drive.google.com/file/d/1QbG5kXiJU1tUz0rlVdBYq28D_CQXfCCq/view?usp=drive_link
At this point I’m not sure what is triggering the recovery mode, so I would greatly appreciate any insight or suggestions.