Sapphire AMD Radeon HD 7950 Mac Edition 3GB Video Card Not Booting

[caliguy1965]

Well Onath adamantly told Ebay that the card did not work at all (not just in his environment, which is not my fault) and they let him return for a refund.
I popped the card into my Mac Pro and it worked perfectly. So I relisted it $50 higher than I sold to Onath and it sold within a day and buyer already installed and left positive feedback.
THANK YOU ALL for the help with this issue, I appreciate it.

 

[Azzaboy18]

I had the same problem yesterday with the looping chime and I have worked out what the problem was (in my setup)
I ran a few tests and I have the following results :
MDP-passive hdmi-FHD
MDP to 4K60
Hdmi to FHD
Won’t boot
—————-
MDP to 4K60
Won’t boot
—————
MDP-passive dvi-FHD
MDP to 4k60
Hdmi to FHD
Won’t boot
—————-
MDP to 4k60
Hdmi to FHD
DVI to FHD
Won’t boot
—————-
MDP-active DVI-HDMI-FHD
MDP to 4K60
Hdmi to FHD
Works!

I don’t appear to have any problem using 4K30 (meaning if I set my monitor to DP 1.1 instead of DP 1.2)

Conclusion:
It appears the only way I can get it to boot while having a 4k60 monitor is to have a display connected to Apples active DVI adapter and have that adapter connected to the mini display port on the left. I guess the EFI can’t boot without a screen and it just can’t handle the 4k60.

In my working setup, only the screen connected to the active adaptor works in the EFI, the HDMI screen and the Mini DP 4K60 screen work once the OS boots.

If I connect the 4K into the 1st MDP port and the active adapter into the 2nd MDP I will get a grey screen on the active adapter screen but the Mac won’t boot.

Hope this helps anyone in the same situation

 

[scruti]

Effectively. I have a MacPro 2009, 4.1, upgrade to 5.1 by EFI.
Quad-Core Intel Xeon, 2.93GHz. AMD Radeon HD 7950. A Dell 1920x1200 monitor and a 4K Benq SW271. I just installed Mojave, and the only way to boot is:
DisplayPort on the left with the DELL monitor with DVI to DP converter
DisplayPort from the right to BENQ 4K to have 60HZ with 3840 x 2160
Now they are perfect.