I cant get display out of a gpu in bios when uefi only is enabled

[Helpful Tech Witch]

Al part of my day long journey to get secureboot and tpm enabled, I had to enable uefi only mode. 

Now, I only get video signal in the bios when the gpu is out of the system, and I'm using the igpu HDMI out. it also takes nearly 5 minutes to boot into windows when the gpu is being used for video out.

When uefi only mode is not enabled, and I have legacy boot as a option, I can boot within seconds, and go into the bios with my dgpu.

How can I fix this?

 

B250m bazooka

i5 7400

Rx480->580 with overclock added

[m9x3mos]

When you say 480>580 is that a custom bios or what? 

Sounds like the card is having trouble supporting uefi.

[Helpful Tech Witch]

17 minutes ago, m9x3mos said:

When you say 480>580 is that a custom bios or what? 

Sounds like the card is having trouble supporting uefi.

yeah, I changed a single byte from c6 to e6, it gets the card to report itself as a rx580, without any issue like it cooking it's core with 1.5v. I also upped the power limit limit, core clock limit, mem clock limit, and upped the core and mem clock stock.