I've got two DP1.2 4K 60Hz displays connected to my 7950 full time. I'm on 10.13.6 and it boots fine, w/ no EFI screens. The trick is to leave it in PC ROM position on the switch. In the Mac position it cannot boot, locks up. High Sierra updated the boot ROM, so I don't expect much trouble upgrading to Mojave. Am I being over-optimistic?
I used this video and the text below it in YouTube app to flash my 7950. Really easy procedure. After that I have EFI boot and I can choose between Mojave and windows 10
INSTRUCTIONS FOR FLASIHNG FROM THE VIDEO:
The forum thread is here that started it all:
http://forum.netkas.org/index.php/top...
In that thread, post #1 is the link to the script you need to run on OS X to take the ROM file you dump from your card and put it together with the EFI portion so you get the boot screen on a Mac Pro.
The one you see when you hold down the Option key to select a boot drive.
Video uses an MSI Twin Frozr III 3GD05/OC and the UPC label of that card is shown in the video.
(My card is AMD Radeon HD7950 Vapor X,, exactly same procedure)
Steps to take before watching this video: I assume you have your card installed properly. I had two six pin power cables already in my Mac Pro from my Radeon 4870 and the MSI card I used came with a 6 to 8 pin adapter. The box says two six pin adapters are ok and based on my research that's fine for the max power draw of this card. 275 watts if I remember correctly. Make sure the tiny BIOS switch at the top of your card is in the '1' position. Consult the manual.
🙂 Here's the text version.
The video explains in a little more detail and shows the script running, some stuff on WINFLASH, etc.
1. Get a blank USB thumb drive. It can be small, 1 gig is plenty.
2. Format the thumb drive using Disk Utility and rename the drive to '7950' without quotes. No spaces in the name!! The script that creates your ROM won't work with spaces in the volume name. Really. Unpack the files from the forum link above to this USB drive.
3. Get a copy of Windows installed you can boot on your Mac Pro.
4. Boot into that and download ATIWINFLASH from here:
https://www.techpowerup.com/downloads...
5. Run WINFLASH.EXE and save a copy of your ROM. Save another copy somewhere like Dropbox. Put a third copy on the USB drive and rename it cardname.rom
6. Boot into OS X. Open a terminal, and change to the USB Drive.
Run the script. (This is shown in the video.) for MY part number, the command is:
./makerom.sh --efifile=7950mac.efi --romfile=efiromheader.rom --originalrom=cardname.rom --devid=679a
Breakdown: .sh is the script itself, the first argument is the mac efi part from the mac version of a 7950 card, the header file, the name of your ROM you saved using WINFLASH to the USB (we called it cardname.rom) and the the device ID that WINFLASH told you for YOUR CARD. ** So the only modification you might need to that command is your device ID.**
7. Boot back into Windows run WINFLASH.EXE, and open the created EFI rom called cardname.rom.efi.rom. Program it to your card.
8. Reboot after the shutdown and enjoy seeing the Apple Logo and your screen before boot, so you can do things like select your boot volume, such as recovery. Very important to have this capability.
Advantage: this card runs at about 20% faster clock speeds than the Mac version. It has dual cooling fans. You could overclock the PC rom and then tack on the EFI portion. That's why you save the original ROM so then you can hack on copies of that all you want.
Disadvantage: All the outputs work, but so far only two at a time. Which is enough for me. Will post if I get a solution.
UPGRADING TO MOJAVE:
After that I followed instructions from here in order to upgrade to Mojave, firmware included:
https://forums.macrumors.com/threads/mp5-1-what-you-have-to-do-to-upgrade-to-mojave.2142418/
Very satisfied and grateful to all authors
MacPro (early 2009). 4,1>> 5,1 - 2 x 3,33 Ghz 6-core Intel Xeon - 32 Gb 1333 DDR - AMD Radeon HD7950 VaporX 3072 MB - NVMe Samsung EVO 970 1Tb- AHCI SSD 250 GB - MacOs Mojave 10.14.2 - Windows 10