OK something quite strange is happening. The fan "problem" still exists as I mentioned it.
The "Quiet" BIOS on my RX580 which I mentioned earlier didn't work with CSM off, turns out that it works
BUT The red light (VGA) on my Designare z390 stays lit and nothing is displayed on the screen until I get to the MacOS login. Not even BIOS screen, no macOS loading nothing. The VGA light on the MoBo remains lit all the way through. Any ideas what that might be? (Checked the clocks on both modes, they are as expected so chances of modified VBIOS are lower)
Fan still never goes higher than 25% (in my standard "Performance" Bios of the GPU) even at 75 degrees.
Maybe it’s just the aggressive MacOS fan curve, waiting to ramp up at something like 80? Or is it not communicating correctly with the OS? How are your RX 580 nitro+ special Edition fans spinning?