Hi there. I have been trying to downgrade the BIOS on my H110M-D motherboard to allow it to use an Engineering Sample CPU (QH8F). Any version from mid year 2016 (In my case, only the last one didn't support it) and below should work for this, according to most websites, so, since EZ Flash wouldn't let me install any older BIOS files (It initially came with one of the year 2017 releases), I used a bootable USB drive with AFUDOS to get the job done. However, although this time it managed to boot up to the American Megatrends post screen where you are asked to set the new BIOS settings, and also correctly recognized the CPU as an ES (Genuine Intel CPU 0000), once I pressed F1 to access it, a message popped up asking for the .cap file in order to complete the installation.
Once I got the file on the USB stick and selected it, everything seemed fine, giving me a success message and finishing the installation. Unfortunately, the same first message appeared after rebooting, asking for the .cap file once again.
No matter how many times I repeated the process, nothing would change unless I installed a .cap file for a newer BIOS version, which would update it, but the loop persists for every BIOS I attempted to install up until version 2002 inclusively, either using AFUDOS and the /GAN command from a post-version 2002 BIOS (which install and work fine, but won't support the ES CPU), or using EZ Flash 3 to update to a superior version.

The other CPU I'm using for downgrading from newer versions is a Pentium G4560. Only version 2002 seems to support both at the same time, but for both of them I get the exact same boot loop I explained before. After that version (3016 and up), the BIOS install just fine, and run properly on the Pentium while not even posting when using the ES, as expected.
At first I thought this was a missing microcode issue, but after managing to modify both a pre 2002 and a post 2002 versions and trying them out, I'm getting the same exact results for each case.

I have made sure that I'm using the proper BIOS files, a FAT32 formatted USB drive, renamed the .cap files to what the manual asks (H110MD.CAP), that CSM is always enabled any time I attempt to downgrade, and pretty much followed every step for anything I tried. I also tried clearing CMOS but this didn't do much either.
The QH8F has a reputation for not working on many consumer boards, but I've seen posts from people running it on different ones, and judging from the kind of errors I got and the fact that the boot loop can also occur with the Pentium, I believe this is something that has more to do with the BIOS and the motherboard itself, and that it would probably work if I managed to get one of the older BIOS versions installed, but I may be wrong.

Any help is welcome. Although this is more of a fun, experimental project and I don't mind the risks of doing this kind of procedures, we have been trying for weeks to get it working, and I'm not sure if at this point I should just get a different motherboard with better ES support, like a Z170 series.