Guys, I need help. I have install a M6000 into several imac 12,2 2011 27" imacs this past 6 months but now I'm having a problem. My previous installs I have upgraded the CPU with an intel Xeon e3-1275 but this time I'm using an i7-2600. This may or may not have something to do with the problem.
My issue is this: Upon a cold power-on boot, OCLP picker works, the default Big Sur partition boots and after the inital Apple Logo appears for 3-4 seconds the screen clears, the backlight comes on but I get no output displayed (blank screen). I know the imac is now waiting for login but nothing is on the screen. This only happens on power-on, not on reboot.
I can work around this issue 2 ways, one is at the OCLP picker menu hit space and choose "reset nvram" and reboot. Upon reboot the OCLP picker auto-starts the Big Sur partition and this time the graphics come up. The second way is to again hit space and choose "recovery", let recovery boot then reset and again the OCLP picker auto-starts Big Sur and this time the graphics work.
I have built OCLP using the latest 0.6.1 but I am finding that using any GUI version I cannot set the MMX GPU type to AMD (GCN) in Developer settings, it will not stick. So I rebuild OCLP with the last TUI (0.4.10) and followed the instructions on the "complex to manage" page with the same results.
One other thing, if I build OCLP with 0.2.4 TUI and install it, OCLP picker comes up, default Big Sur boots, Apple logo appears, disappears, then the imac reboots (OS crashes) and at the second reboot again everything starts fine. I then compared config.plists (0.6.1 with 0.2.4) and removed all the 0.6.1 unique settings so it matched the 0.2.4, but the same results - no graphics. What am i doing wrong? I thought it might be related to the iGPU on the i7-2600 but that appears to be disabled by OCLP.