Hello to everybody,
I have a general query. Can anyone edit the BIOS so that it supports (or added to BIOS) the CSM mod? For use with old HW or is it not possible?
My NEW MB officialy support UEFI ONLY ! 
I would send the model of the manufacturer and model.
Thank you
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@OndrejCZE :
Welcome to the Win-RAID Forum!
AFAIK all UEFI BIOSes offer the option to ENABLE the Compatibility Support Module (CSM) and to use LEGACY mode Option ROM modules.
So I think, that there is no need to modify the BIOS.
Regards
Dieter (alias Fernando)
P.S.: I have moved your request, which is not Forum related at all, into the better matching āBIOS Moddingā Sub-Forum.
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If you post your motherboard model someone will be able to help show you which section of the BIOS has the CSM setting
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Hi,
my model main board is : ASRock J4105M
http://asrock.com/mb/Intel/J4105M/index.asp#Specification
Thank you
@OndrejCZE :
Please look into your mainboard manual for the CSM and Option ROM setting options within the BIOS.
Itās there, but set to disabled (UEFI) by default if āfail-safeā BIOS settings used, all you have to do is change to enabled and then set how you want.
Load optimal defaults first, then reboot back to BIOS. That will put it to legacy enabled by default, only fail-safe is UEFI Only/Legacy Disabled by default.
Setup >> Boot >> Boot >> CSM
Hi Bugger Vance,
could I ask you to modify the bios where this CHS option could be added?
Just so you can choose whether UEFI or Legacy mode.
Instant Flash under BIOS: ftp://europe.asrock.com/BIOS/CPU/J4105M(1.00)ROM.zip
Thank you very much
@OndrejCZE :
As Bugger Vance has explained, there is no need to modify the BIOS. You just have to choose the related BIOS settings.
Hi @OndrejCZE
Fernando is correct, the option is already there so no need to add. Did you look in the BIOS where I mentioned? You should see all the options to enable/disable, and to choose which option roms you want set to UEFI or Legacy.
Hello,
today I looked at it and the default is only load default. Load FailSafe I do not have it at all Thatās why I wrote whether it is possible to change values firmly.
However, I tried it myself through the same program you sent Screens. And the adjustment will take place. Iāll save the BIOS, but if I want to flash it, it will write a bug right away. Something with checksum error ā¦ So maybe the board knows thereās something wrong
Fail-safe may only load automatically when something fails (like overclock failed etc). Nothing to worry about there anyway, you donāt want fail-safe loaded ever really, I only mentioned it because that is the only state that has EUFI only / Disabled CSM/Legacy.
That is why I said, āLoad defaultsā then reboot back to the BIOS. Then go here Setup >> Boot >> Boot >> CSM as shown in above image, in that section you will find the CSM settings.
Nothing needs changed in the BIOS, that is why I did not modify a BIOS for you, it is all available by default in the non-modified stock BIOS. No changes are needed to the BIOS
To flash a modified BIOS you would probably have to use DOS, or ācorrectā the modified BIOS per the methods listed here.
At the end of the Asrock section in first post, right before āGigabyteā section starts,there is 2-3 methods mentioned for newer Asrock BIOS like this one without a CAP header.
[Guide] How to flash a modded AMI UEFI BIOS
BIOS modifications shouldnāt be needed for the CSM settings, they are there and enabled to be visible to user by default.
Did you go into boot section, then at bottom of that page go into secondary boot setting page, and not see all the CSM user settings?
If not, please post a few images of what you see in those pages of the BIOS, then if a mod is needed I can do for you if you want.
But I donāt think itās necessary, all there visible/enabled to user by stock BIOS
I understand, Iāve been moving in IT for a long time, so I know where to look.
This afternoon I will run screens from the BIOS and send it here to the forum.
This is a new type of record. Interestingly, this new board does not even boot from the UEFI USB flash. Other UEFI bios boards normally boot from my created UEFI USB flash drives.
Here is just UEFI support.
Interestingly, if I opened the BIOS like you, there are items that are not visible in my bios
EDIT:
Thank you for mod.
Some boards are picky about the size, brand, or file system of USB drives especially when booting from them, that could be part of the USB issues you mention.
Thanks for mentioning youāre knowledgeable in tech, some of your replies were short and non-descript so I wasnāt sure how comfortable you were about digging around in the BIOS
Thanks for the images! I checked the BIOS and see āFail-safeā isnāt an option that can be enabled for the save/exit screen, itās set automatcially by the board in some instances.
No big deal, we dontā need or want to enable fail-safe anyway.
Can you please show me an image of boot menu section, last tab on right side top. And then image of the next page inside boot section, after you go into last sub-page from bottom of the boot section.
Thatās what youāre needing help with surprised to not see you post images of that page first!
There is no mention of the legacy 
Thanks! That first image, I assumed under āfull screen logoā there would be more options, either more settings or another sub-page. At least that is how it appears in the BIOS structure and settings shown in AMIBCP.
Looks like you do need a mod, let me see what I can do. Iāll also look and see if there is any setting possibly stopping USB boot (be sure you try USB 2 ports, sometimes some USB 3.0 might not be bootable).
Will post back in a few with couple mod BIOS for you to try.
Did you already try loading optimized defaults, then rebooting and trying whatever legacy device you were wanting to use and it still failed to work? Optimized should load ālegacy onlyā devices enabled, but may not be showing you the CSM setting, but looks like it should be enabled for legacy once optimized is applied.
@OndrejCZE
Try this Mod BIOS and see if CSM options show in boot tab section.
I also made a few USB changes too, so maybe USB boot device will work for you now, fingers crossed
https://nofile.io/f/03mC2hcvRy8/GLKM1.M2.zip
I did notice that it looks like if you use UEFI secure mode (password locked with keys I think), then CSM cannot be used.
I am not sure about all that though, have never used secure modes so Iām not certain how all that applies.
Thank you for moding the bios. But it killed my motherboard 
see. the enclosed video.
I apologize for the video being turned.
So I have to return the motherboard under warranty.
@OndrejCZE
So sorry that happened! You donāt have to do warranty RMA, you can buy programmer on ebay for $3-5 (SPI flash programmer CH341A) and reprogram the chip with stock BIOS, itās very easy to do and only takes 1-2 minutes
I see press F2 or Del to enter BIOS (Not space key, looks like you press space due to it saying āPause pressedā), did you try that yet F2 or Del? I hear you press key, not sure which though.
If you can get in there you may be able to reflash stock BIOS. Same for DOS, if you can boot to DOS vis USB or CD then you can reflash with AFUDOS or the Asrock DOS flasher.
If you can get to a āBoot Menuā via F11 at startup Iām certain it can be recovered via DOS flash!
It doesnāt look as bricked to me as you might think, you may be able to reflash via BIOS if you can get in or should be able to via DOS, without having to wait on a flash programmer
Any progress on this? I have same model, and i canāt pxe boot because it doesnāt support Legacy bootā¦
I wouldnāt mind testing custom bios as long as thereās a clear reflash instructions in case things go wrong