https://forum.asrock.com/ Copyright (c) 2006-2013 Web Wiz Forums - All Rights Reserved. Sun, 10 May 2026 14:07:12 +0000 Mon, 23 Mar 2026 20:01:10 +0000 http://blogs.law.harvard.edu/tech/rss Web Wiz Forums 12.04 360 https://forum.asrock.com/RSS_post_feed.asp?TID=113476 https://forum.asrock.com/forum_images/web_wiz_forums_black.png https://forum.asrock.com/ https://forum.asrock.com/forum_posts.asp?TID=113476&PID=201104&title=b850mc-no-display-until-os-loads#201104 Author: Xaltar
Subject: 113476
Posted: 23 Mar 2026 at 8:01pm

I don't know your specs but some older GPUs rely on CSM for their OP ROM loading.
This is also true of somewhat newer Enterprise/workstation GPUs. Other than that
I couldn't guess. If you get stuck anywhere else feel free to ask here.]]> Mon, 23 Mar 2026 20:01:10 +0000 https://forum.asrock.com/forum_posts.asp?TID=113476&PID=201104&title=b850mc-no-display-until-os-loads#201104 https://forum.asrock.com/forum_posts.asp?TID=113476&PID=201103&title=b850mc-no-display-until-os-loads#201103 Author: lordfoo
Subject: 113476
Posted: 23 Mar 2026 at 7:35pm

Thank you for your time, and quick response.

The older drive has Linux. It was installed sometime 3-4 years ago. I do not recall how it was installed, but I am pretty sure it uses GPT (Linux defaults for many years, now) I am trying to create a bootable USB drive with Ubuntu on it to test.

I don't like Windows, but I unfortunately need it from time to time. So, having two device might be a permanent solution.

In the BIOS, it has a warning about CSM, because I have a AMD GPU plugged in, and while it may have listed the other device, enabling the CSM requires me to reset the BIOS to actually see the bootloader!!

I have no idea why the CSM would affect the GPU.]]> Mon, 23 Mar 2026 19:35:30 +0000 https://forum.asrock.com/forum_posts.asp?TID=113476&PID=201103&title=b850mc-no-display-until-os-loads#201103 https://forum.asrock.com/forum_posts.asp?TID=113476&PID=201102&title=b850mc-no-display-until-os-loads#201102 Author: Xaltar
Subject: 113476
Posted: 23 Mar 2026 at 7:27pm

It sounds like your old drive was running Windows 10 and was set up with an MBR
partition. Windows 11 requires GPT mode which is the default on newer motherboards.
Enabling CSM in your boot options would allow your old drive to be detected and
bootable, however, windows 11 on the new drive won't like it. CSM stands for
Compatibility Support Module and exists to support older devices and hard disk
formats on newer hardware. In the past the default setting was CSM enabled, now
however this is being phased out and the default is CSM disabled.

TLDR, if you install your OS with CSM enabled that drive will not boot with CSM
disabled. There are means to convert an MBR partitioned drive to GPT but it's
a lot of effort and there is always some risk of data loss.

If you want to only occasionally boot from the older drive all you need to do
is pop into the BIOS and enable CSM before booting then once done using it you
can pop back in and disable CSM to boot from your windows 11 drive again.

Hope this helps.]]> Mon, 23 Mar 2026 19:27:51 +0000 https://forum.asrock.com/forum_posts.asp?TID=113476&PID=201102&title=b850mc-no-display-until-os-loads#201102 https://forum.asrock.com/forum_posts.asp?TID=113476&PID=201101&title=b850mc-no-display-until-os-loads#201101 Author: lordfoo
Subject: 113476
Posted: 23 Mar 2026 at 7:20pm

Yes, the system boots just fine. But I want to be able to boot using a different UEFI-enabled hard drive. The BIOS did list it, but the screen went blank when loading from it. And this is when I realized that I had no more display in the BIOS.

I did find a jumper from an old motherboard and reluctantly did the jumper procedure. The BIOS display is back, but I can no longer have my secondary device displayed in the boot menu (F11 at boot).

Windows 11 shows the device just fine! So it is there! And I know it has UEFI because this was the same SDD I used in my previous system (Linux).

Strangely, I plugged a USB thumb drive and the BIOS lists it just fine even though there is no UEFI or boot sector on the device. ¯\(??/¯

I don't get it.]]> Mon, 23 Mar 2026 19:20:35 +0000 https://forum.asrock.com/forum_posts.asp?TID=113476&PID=201101&title=b850mc-no-display-until-os-loads#201101 https://forum.asrock.com/forum_posts.asp?TID=113476&PID=201100&title=b850mc-no-display-until-os-loads#201100 Author: Xaltar
Subject: 113476
Posted: 23 Mar 2026 at 6:53pm

It would be helpful to have your full system specs.

I am assuming that you had a display before you played with boot options? If that
is the case then you should be able to just clear CMOS, if that is what is making
you uncomfortable then you can achieve the same effect by removing the button cell
battery from the motherboard while the system is disconnected from power.

1. Turn off the system
2. Disconnect the power cord
3. Press and hold the power button for a few seconds to ensure there is no
residual power being held in the board and power supply's capacitors.
4. Remove the side panel from your system
5. Pull the little tab at the edge of the battery outward, the battery should pop
up and then can be safely removed.
6. Leave it out for a few minutes.
7. Replace it and reconnect everything.

Alternatively, you can be brave and after step 4 above, short the clear CMOS pins
on your board using the provided jumper, simply move it from pins 2 and 3 to
pins 1 and 2 then back again. With the board fully powered down in this way there
is 0 risk of damaging anything.

Good luck ]]> Mon, 23 Mar 2026 18:53:32 +0000 https://forum.asrock.com/forum_posts.asp?TID=113476&PID=201100&title=b850mc-no-display-until-os-loads#201100 https://forum.asrock.com/forum_posts.asp?TID=113476&PID=201098&title=b850mc-no-display-until-os-loads#201098 Author: lordfoo
Subject: 113476
Posted: 23 Mar 2026 at 5:54pm

This is a new computer, using a B850M-C motherboard. I had issue getting the UEFI to detect a secondary boot device, so I played around with the confusing boot options. Suffices to say that now the system boots with a blank screen until it gets to Windows 11.

Restarting the PC with SHIFT pressed does restart into the BIOS, but with a blank screen. I removed the GPU, nothing. Tried every different video output. Nothing.

I am NOT comfortable playing with the PINs on the motherboard!

My previous computer was also an ASRock, worked fine for 12 years! This one, however, 2 days in and already this issue.

How can I get video output in the BIOS?]]> Mon, 23 Mar 2026 17:54:05 +0000 https://forum.asrock.com/forum_posts.asp?TID=113476&PID=201098&title=b850mc-no-display-until-os-loads#201098