Hi

I had previously loaded unlocked Bclck with Provided unofficial BIOS for Z170 motherboards , as you can see here , there are many unofficial BIOS for unlocking the Bclck, on Z170 motherboards . :
Source 1
Source 2
I previously had a 6500 running at 4.5Ghz on a GA 170 ( Gigabyte ) board . This was around a year ago .

Today I flashed an ASUS Z-170 P , I flashed using a FreeDOs USB with the 'AFUDOS.exe' program . The board was previously running a 2018 BIOS ( 3805 ) with ME Firmware 11.8.50.3470. I downloaded the custom firmware from the HWBOT link in 'source 2' above . THe flash ran, it verified 100% , I restarted the machine , once , twice and relised I was stuck in the 'ASUS EZ flash' menu , It asked for the 8008.CAP, which I used to flash again . Ever since , I have been stuck on an 'EZ Flash ' menu , that fails to run with any USB drive connected . As shown



Luckily this Motherboard has a socketed type of EEPROM BIOS chip, and I can get a preflashed version for this board . However I am curious why this did not work out ? Is the BIOS and ME Firmware Related ? Does the ME Firmware prevent older or modded BIOS versions from working at all ?

So today I ordered a BIOS chip pref-lashed with Factory stock BIOS (first release) . According to the supplier the original Stock BIOS will not have the ME firmware , according to him the replacement chip will work because it does not have the ME firmware code .

Only time will tell to be sure .

@90Ninety - You need/want ME FW, he's lazy is the issue there! Without it you can have fan speed 100%, many CPU functions will not work properly, including CPU speeds/multi, memory speed/timings etc
You will need CH341A flash programmer to fix that, and U Type Flat IC Extractor if BIOS is in socket

The original issue you had may have been random glitch, or you were on too new of BIOS or ME FW to properly downgrade to those special BIOS. You can't downgrade ME FW via BIOS flash generally, you need flash programmer or to unlock FD and allow access to ME region then downgrade it with FPT.
So, could also be due to that later stuff, you on new BIOS and then special BIOS needs the older ME FW which you couldn't flash it, so it was stuck partially flashed to the intended target BIOS as a whole.