Dual 4K@60Hz GFX Card for Mac Pro

mrhansolo

macrumors member
Original poster
Oct 24, 2011
37
3
Hello,

I have been reading through threads all morning and think I almost have things figured out. Just have a couple of questions to conform things and a couple more to to see if there is an answer that I haven't found yet.

I'm running a Mac Pro 5,1 with 10.13, and looking to buy two LG 27UD68P from a local business. I do general web browsing, word processing, light Photoshop Work, InDesign work, and I also run Windows (via Parallels) to use ArcGis in my second screen. I would like to stay around the $260 price range or less.

From looking at things, the Radeon 7950 or 7970 (flashed and resistor removed) is the most economical option for what I'm wanting. However, there are a few questions that I am unable to find answers to.

- Can the 79xx series power two 4K screens at 60hz via Displayport?
- Is there anything that might lead to a compatibility issue as far as the monitors go? In some older threads I saw where you have to specifically set a display port setting or the monitor had to be set or MST over SST.

Hoping someone can jump in and fill in the blanks so I can go ahead and buy a card. Of course I'm always open for other suggestions outside of the 79xx series. I just don't want to have to worry that every time an update comes out I am going to lose my video card or have to reinstall drivers.

Thanks,

Han
 
Last edited:

h9826790

macrumors G5
Apr 3, 2014
14,146
6,781
Hong Kong
Hello,

I have been reading through threads all morning and think I almost have things figured out. Just have a couple of questions to conform things and a couple more to to see if there is an answer that I haven't found yet.

I'm running a Mac Pro 5,1 with 10.13, and looking to buy two LG 27UD68P from a local business. I do general web browsing, word processing, light Photoshop Work, InDesign work, and I also run Windows (via Parallels) to use ArcGis in my second screen. I would like to stay around the $260 price range or less.

From looking at things, the Radeon 7950 or 7970 (flashed and resistor removed) is the most economical option for what I'm wanting. However, there are a few questions that I am unable to find answers to.

- Can the 79xx series power two 4K screens at 60hz via Displayport?
- Is there anything that might lead to a compatibility issue as far as the monitors go? In some older threads I saw where you have to specifically set a display port setting or the monitor had to be set or MST over SST.

Hoping someone can jump in and fill in the blanks so I can go ahead and buy a card. Of course I'm always open for other suggestions outside of the 79xx series. I just don't want to have to worry that every time an update comes out I am going to lose my video card or have to reinstall drivers.

Thanks,

Han
Yes, each of them can drive two 4k 60Hz monitor at the same time (each monitor connected to a display port in SST).

HOWEVER, both of them CANNOT display boot screen at 4k 60Hz. In fact, if you boot from Mac EFI ROM when connected to a 4k 60Hz monitor. The cMP will hang.

The work around is set the monitor to DP1.1 BEFORE you power up the Mac, let the boot screen shows at 4k 30Hz, and then set them back to DP1.2 ON EVERY SINGLE BOOT.

IMO, unless you are using FileVault. It’s better to boot from the PC VBIOS, so that no need to mess around the DP setting. And only switch to the Mac EFI ROM
when absolutely required.
 
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mrhansolo

macrumors member
Original poster
Oct 24, 2011
37
3
Yes, each of them can drive two 4k 60Hz monitor at the same time (each monitor connected to a display port in SST).

HOWEVER, both of them CANNOT display boot screen at 4k 60Hz. In fact, if you boot from Mac EFI ROM when connected to a 4k 60Hz monitor. The cMP will hang.

The work around is set the monitor to DP1.1 BEFORE you power up the Mac, let the boot screen shows at 4k 30Hz, and then set them back to DP1.2 ON EVERY SINGLE BOOT.

IMO, unless you are using FileVault. It’s better to boot from the PC VBIOS, so that no need to mess around the DP setting. And only switch to the Mac EFI ROM
when absolutely required.
Thank you for the quick reply. Going to research the process of switching to VBIOS. I don't use Filevault, so if that is the only hangup then I don't see why I wouldn't switch. As long as it doesn't break having any future updates, etc.

Edit: I think you mean don't flash the card at all? Which would result in the monitors being blank until until the OS is loaded correct?
 

h9826790

macrumors G5
Apr 3, 2014
14,146
6,781
Hong Kong
Thank you for the quick reply. Going to research the process of switching to VBIOS. I don't use Filevault, so if that is the only hangup then I don't see why I wouldn't switch. As long as it doesn't break having any future updates, etc.

Edit: I think you mean don't flash the card at all? Which would result in the monitors being blank until until the OS is loaded correct?
No really “not flash at all”, the reference 7950 or 7970 has two ROM (whenever you want to flash these cards, better stick to reference card). You can flash ROM 1 to Mac EFI. And leave ROM 2 as stock UEFI / legacy ROM.

And in your setup, for your daily use, boot from ROM 2. So, no boot screen until drive is loaded.

On the day you really need boot screen. Shutdown the Mac, switch the monitor to DP1.1 and boot your Mac from ROM 1.

There is a little switch on the card, I can easily flip the switch in 10 seconds (including the time to open and close the side panel). Nothing rocket science, just a little physical switch on the graphic card near the Crossfire connector.
 
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mrhansolo

macrumors member
Original poster
Oct 24, 2011
37
3
No really “not flash at all”, the reference 7950 or 7970 has two ROM (whenever you want to flash these cards, better stick to reference card). You can flash ROM 1 to Mac EFI. And leave ROM 2 as stock UEFI / legacy ROM.

And in your setup, for your daily use, boot from ROM 2. So, no boot screen until drive is loaded.

On the day you really need boot screen. Shutdown the Mac, switch the monitor to DP1.1 and boot your Mac from ROM 1.

There is a little switch on the card, I can easily flip the switch in 10 seconds (including the time to open and close the side panel). Nothing rocket science, just a little physical switch on the graphic card near the Crossfire connector.
Thank you. One last clarification, will all 7950/7970 have these switches? The main card i'm looking at is a nicely priced MSI Radeon 7950.
 
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