Mysterious UEFI Behavior on Biostar AM1MH with AMI v4 BIOS

[Eschaton]

I want to relate an interesting thing I discovered with an AMI v4 (IV) UEFI -based motherboard I purchased recently - after I clear CMOS, the next boot I get a screen that shows me I can overclock to 3.6ghz using a base clock multiplier change, whereas on every boot thereafter UEFI shows what the manufacturer actually claims for the board, which is that you can only underclock (2.2ghz and lower, down to 800mhz):

Picture of the overclock setting working

Picture of what the options are after reboot

My system setup's relevant bits are as follows:
CPU: AMD Athlon 5370
Motherboard: Biostar AM1MH Motherboard
UEFI Version: AKBAT411
RAM: 1x4gb Crucial DDR3 RAM
HDD: 250gb SATA II Western Digital 7200rpm

The UEFI is plainly not working as intended here, but what's most interesting to me is the possibility that the higher base clock values could be permanently enabled if only we could modify this AMI UEFI appropriately. I am a total novice at this, but I was able to get a little headway by downloading the UEFI file from Biostar (they give it to you as a .bss file) and renaming it as a .rom file. This ROM was readable by AMIBCP v. 4.53
  AMIBCP 4.53.0050.zip (Size: 309.1 KB / Downloads: 9) , which gives me the following:

   

The "USER" allowances were added by me; before they all said "Default."

Up to now, that is all the editing of the file I've done  . I haven't flashed it yet because I don't know if I will brick my device in so doing and I don't even know if it will accomplish what I want to do.

Can anyone point me in the right direction for unlocking the overclocking values in this BIOS? If you want to fiddle around with it  yourself you're certainly welcome to; I've included all the necessary data as attachments to this post. What's in it for you? I think if we can figure out how to do this here, then many Biostar BIOSes will benefit from the same modification; I think they tend to reuse this UEFI on multiple boards. This could be the start of a widespread edit helpful to many other people as well, especially since the AM1 community is starved for motherboards with good UEFIs.

[Eschaton]

A quick update on my progress... I'm afraid I can't get much further without understanding 

1. If my modification will be safe.
2. If it will even work.

I'm actually currently GUESSING that it will in fact be safe, but that it will not work. This is because the overclocking menu is available, but some of the menu items are not, so I don't think making the Custom FID menu set to "USER" will change anything - I'll have to find a way to reveal multipliers 22.5-36, which are the hidden items. If possible, it would also be good to reveal Core VID settings above 1.325, which is the default and will not yield as high of a stable OC. 

I have started to try to use UEFITool NE A32 to get a closer look at this BIOS, 

  UEFITool_NE_A32_win.zip (Size: 3.39 MB / Downloads: 9)
but I'm afraid I don't really understand that program. I was able to use it to find what I think are the hard representations of the hidden multiplier strings, 
   
and also "BIOS String" representations thereof,
   

But I don't know what kind of edit I need to make in order to make these strings (and associated settings) visible and select-able. 

Anyone have a clue?

[Eschaton]

Is it possible to change the x8 default to a higher multiplier and get the overclock that way? Seems like a very dangerous course of action because obviously if we get stuck on a totally unstable clockrate the system is essentially bricked...

[Eschaton]

So how useful is this site, anyway? I really need help and I'd like to move along. Should I post this stuff elsewhere? What are some more active sites for BIOS modding out there?

[Eschaton]

Thanks to help from some folks in PM, I think I'm gonna have to use Universal IFR Extractor as my tool to find and remove EFI_IFR_SUPPRESS_IF statements...

[Eschaton]

Quick update: Universal IFR Extractor 0.5 is unable to read the protocols of the modules extracted from the UEFI's .rom file using MMTool 4.5 or 5.0. I'm guessing I'm doing something wrong, but I can't figure out what...

[DeathBringer]

Look into module with GUID {899407D7-99FE-43D8-9A21-79EC328CAC21}

[Eschaton]

Look into module with GUID {899407D7-99FE-43D8-9A21-79EC328CAC21}

Yep, this looks very promising. I've included the .txt body extraction file as provided by UEFITool: 
  Setup_Compressed_section_body IFR.txt (Size: 328.37 KB / Downloads: 21)


This definitely is something we can work with, modify, and potentially insert back into the BIOS using UEFITool again!

First of all, thank you, DeathBringer!!! Second, how did you determine the importance of that particular GUID, if you don't mind me asking...

[DeathBringer]

I just opened some modules from biggest.

[Eschaton]

New strategy, based on DeathBringer's help:

In the extracted module, go to line 0x3907B and start deleting "Suppress If: {0A 82}" and "End If {29 02}" lines. This will for sure unhide the menu items, but I am worried it will cause the file to be too different for successful overwriting of the default UEFI...