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Dell optiplex 3040 micro: no multiple displays in BigSur (OpenCore 0.6.3)


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I did a  clean reinstall of  my  Dell optiplex 3040 micro. It use to have it installed with Catalina and Clover, i want to have Big Sur with OpenCore 0.63.

The install succeeded but only  one of the two screens are working .  The HDMI-port  OR  the displayport but not both.  It use to work with Catalina and Clover. 

What do I wrong?  and how can I fix it? .


Dell optiplex 3040

proc.    i3 6100T  (skylake) 

mem:   8 Gb ddr3

graph:   intel HD 530

ether:   realtek 8168

wifi:     intel AC8260




tanya’s macmini.ioreg EFI_3040_1screen_only.zip

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You need to:

  1. inject additional properties for the desired output ports (i don't think you need to inject device-id 1B19 by the way)
  2. change SMBIOS from Mac mini8,1 (a Coffee Lake model) to iMac 17,1 (a Skylake model).
  3. add boot arg agdpmod=pikera to bypass the native graphics output restrictions that apply to the selected (SMBIOS) Mac model

Refer to the link I posted here. You'll then have everything.

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@tanya, you did not inject the properties I recommended. In addition, you've entered a totally invalid property "layout-id" which you should remove.


Make sure you inject the following properties:

AAPL,ig-platform-id          00001219    DATA
framebuffer-patch-enable     01000000    DATA
framebuffer-fbmem            00009000    DATA
framebuffer-stolenmem        00003001    DATA
framebuffer-pipecount        3           NUMBER
framebuffer-portcount        4           NUMBER
framebuffer-memorycount      3           NUMBER
framebuffer-con1-enable      01000000    DATA
framebuffer-con1-alldata     01050900000800008701000002040A00000400008701000003060A000004000087010000   DATA
hda-gfx                      onboard-1   STRING


and add the following boot arg to your NVRAM section, it's mandatory:



Of course, you may also experiment with the ig-platform-id value JakeLo gave in his post.

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tried the above and some other things,   (  ig-platform-id, pikera &  vit9696 boot arg,  multiple framebuffer-con-enable )  but no go...   Both  HDMI and DP  ports are working but  NOT at the same time. 

I guess I had to  downgrade to  Catalina/Clover for dual monitor support:  Tons of people with REAL Macmini's also have problems with Dual monitor setup under Big Sur, especially Big Sur beta and Big Sur 11.0.1   .  I guess it's a Big Sur 11.0.1 thing.   See 120+ complaints on  "macOS Big Sur - Multiple Display "… | Apple Developer Forums "  "https://developer.apple.com/forums/thread/651131"   


My  Latitude 3400, although,  CAN drive two monitors &  laptop screen with Big Sur ( with minor issue:  must pull out and plug in HDMI cable to get it working) 

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With both DP and HDMI plugged in, I  power on.  At first only the DP screen shows the Dell logo,  OC boot menu and apple "-v text" .

When the apple logo appears still a total black (no signal) HDMI screen.  When the Mac login screen appears still a black HDMI screen, but after 6 or 7 second the HDMI screen comes up and stays.   it survives sleep-mode and screen-save mode!   No issues here.




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