RX 580 no video during boot with CSM disabled

[NTICompass]

I just got an RX 580 to replace my RX 460 (the fan broke ) and I am having a weird issue with the new card.

 

With the RX 580 installed, the system powers on but shows nothing on the screen.  No motherboard logo, no Windows loading, but... then Windows actually loads and everything works!

I reset the BIOS, by pulling the CMOS battery, and then when I rebooted, I did get a picture on the screen during boot up.

 

It seems that with CSM disabled, I do not get anything on the screen during boot.  With with CSM enabled, then I do.

 

I've searched around and I've seen things like "update your GPU's BIOS".  It says "UEFI" in GPU-Z, and oddly enough the RX 460 didn't have this issue and worked fine with CSM disabled or not.

 

Is there an issue with my RX 580 and do I need to RMA it?  Is there a way to update the GPU's BIOS without bricking anything?  Should I just leave CSM enabled even though I don't need it on?

 

PC Specs:

ASRock B450M Pro4

Ryzen 7 2700

32GB G.Skill DDR4-3200

XFX RX 580 GTS Black Core Edition 8GB

[NunoLava1998]

Disabling CSM makes your system UEFI-only, while enabling it makes it UEFI and BIOS only. You don't need to RMA and there's no issue with leaving CSM on at all; for most motherboards it's the default option to keep it on

[NTICompass]

But why would making it UEFI-only cause a newer card to not display anything?  Why did my RX 460 work with CSM disabled?