UEFI CSM keeps turning off : can't boot from GPU, always need to plug into IGP!

[BuckChorris]

Just got a Z87N-WIFI mITX / i5-4670 / 2x4Gb combo with a fresh Windows 8 Pro install onto a 120GB SSD, upgraded to Windows 8.1 Pro.

So far so good, everything was fast and snappy and great, except for the "Secure Boot isn't configured correctly" watermark, so I enabled Secure Boot in the BIOS... and I may have fiddled with more settings than I should have... Oops...

Next boot, the PC is stuck in a boot loop : keyboard lights blink on and off, fans speed up and down - both screens stays black, no post, nothing. After much fiddling, clearing CMOS, and more fiddling, here's my situation :
 - PC will be stuck in infinite bios boot loop if screens are connected only to the GPU (Radeon HD 6950),
 - PC will boot only if a screen is connected to the IGP (mobo)

From what I've read, the Compatibility Support Module (CSM) needs to be turned on, and OpRom needs to be set to 'Legacy' for the non-GOP GPU to boot.
I've tried those settings, but it still goes into a boot loop anyway! When I go back into the BIOS, CSM has reverted to 'Never'. AAAARG!

Anyone else got this problem? How can I fix this? It's annoying!

Note: the Secure Boot seems to be configured and working properly, the watermark is gone. Once booted, I can replug my 2nd screen to the GPU and it works fine, but this is not a real solution. AFAIK, there is no bios update to enable GOP on the Radeon HD 6950. Mobo bios is F4.
 

[ysw]

you may check with your graphics card vendor--if you graphica card has UEFI bios/GOP support.
"CSM set to never" need fully UEFI support--m/b, graphics and OS WIN8.

[BuckChorris]

Hi ysw, thanks for your reply. 

I had checked and there is no GOP bios update for the Radeon HD 6950. The card is about 2 years old, "ancient" by modern standards, but still very capable - I won't be changing it anytime soon.

[BuckChorris]

So, nobody has a clue how to fix this? 

[MegaMouse]

graphics card requires UEFI bios/GOP support +1 .. 

[BuckChorris]

graphics card requires UEFI bios/GOP support +1 .. 

Actually, no.

I can now boot from my non-UEFI GPU with both my screens connected to it, with Secure Boot, and for the benefit of others, and to dispel the obvious ignorance on the subject, I will explain the solution.

In the BIOS Features page, set the following:
 Fast Boot = Enabled
  VGA Support = Auto
 CSM Support = Always
 "Other PCI Device ROM Pri" = Legacy OpROM (I presume the "Pri" is for priority...)

Not sure if these need to be set, but I have them enabled :
 Secure Boot Mode = Custom
 Image Execution Policy, Option Rom = Allow Execute

Also, for Secure Boot to work, you need to have loaded the default keys in the Key Management option.

The drawback of running Secure Boot with a non-UEFI graphic card is you can't go into the BIOS; doing so resulted in bios boot-looping again and I had to connect a monitor to the IGP to boot and re-fix the bios settings.

The PURPOSE of the Compatibility Support Module (CSM) is to provide support for "Legacy" ROM, such as non-UEFI graphic cards.
The lack of clear precise information on the subject, even from a support ticket with Gigabyte, is disturbing...

Hope this helps others with this issue.

[BuckChorris]

I got the above solution to work a few times, but it doesn't always work, sometimes it bonks out and I have to reconnect a monitor to the IGP...

Seriously, this CSM/Legacy OpRom support is weak.

[Undermoose]

I had a similar problem with my R9 Nano, CSM would always turn on.

It turns out that there is a BIOS posted for the R9 NANO on the Gigabyte support page, but it has the same version number as the production BIOS on the card...

So GPU-Z doesn't have UEFI check box checked... and CSM keeps turning back on... and the BIOS' seem the same...

I flashed it anyway.

Walla, UEFI now checked in GPU-Z and CSM stays disabled.