It’s been a while since visited here last time. Anyway I got bored and found an Asus board (H110M-K) board from my stocks. Although the board has a weak VRM-section it’s probably fine with stuff like i5 8400/8500 as long as everything is kept at stock speeds.
I used Coffeetime 0.99 to mod the latest official bios update with ME 11.6.10.1196 (mod.rom) and added board specific data (SN,UUID etc.) to mod.rom by using F4DD editor.
I unlocked FD/ME write protection according to this guide. Then I flashed mod.rom to SPI by using AFUWIN 3.05.04 with /GAN command as I did years ago with another Asus board. After that I dumped the newly flashed image file (dump.rom) by /O command and this is what I got
So it looks like that either AFUWIN is incapable to rewrite the FD-region or Asus bioses have separate lock for descriptor. I highlight that ME itself has been changed (originally it was 11.8XXXXX).
I am pretty sure that the mod works fine with B0-revision CPUs but since SKU-modification is not present in the dumped image the system won’t boot with U0 rev. stuff. To be fair, I haven’t yet tested the system with any new CPU.
Other possibilities are to use Intel’s FPT to rewrite FD-region or flash mod.rom with a CH341A -programmer. For the latter option the bios chip is socketed (Winbond 25Q128FV) and I have a programmer but not sure if it’s safe to use. Data lines draw 5V and instead of CH341A it has marking CH341B on the controller chip.
EDIT: As I suspected FD is locked separately. FPTw64 was able to re-flash ME-area but not FD
Error 451: The host CPU does not have write access to the target flash area. To enable write access for this operation you must modify the descriptor settings to give host access to this region.
FPT Operation Failed.
Apparently launching GRUB from efi.shell and then off-setting the re-flash variable only unlocks ME-area in this case.