I will add that IntelRC can be accessed even without BIOS reflashing. With UMAF tool, presumably. Or with SREP and a special config file for it, but making it to work is complex.
You already have the setup_extr.txt which was generated from the 899… module. There should be another one with its own unique number for IntelRC.
You can find it in a BIOS file loaded in UEFI Tool by related strings (OverClocking, Setup Warning). It is possible to extract another .txt using the IFR Extractor.
In AMITSE there are 2 or 3 arrays placed nearby one to another that can be found by searching for the “4a 10 59 7b 0d c0 58 41 87 ff f0 4d 63 96 a9 15 10 27” sequence. The arrays represent lists of forms (like Advanced) to be shown/ignored during final procession.
Each consists of 20h-sized blocks.
For IntelRC it will be the following.
The second F bytes should contain an ID of desired form. If not populated, the parent form will be shown.
If edits done correct, you'll get something like this.
