Three monitors — worked with nVidia, but not AMD

[JordanOrlando]

I had three monitors going, with my old nVidia GeForce GTX 970 (running CUDA) — two identical Samsungs, via DVI and MiniDisplayPort (with an adapter), and a Wacom Cintiq Pro via MiniDisplayPort.

After replacing the nVidia GPU with a AMD Sapphire Radeon HD 7950 3GB GDDR5, I can only run two monitors. When I plug in the Wacom tablet, one of the Samsungs goes dark.

I uninstalled the CUDA drivers (using nVidia's uninstall scripts), and I installed the kexts (Lilu.kext and WhateverGreen.kext) and /Volumes/EFI/EFI/Clover/Drivers64UEFI/EmuVariableUefi-64.efi — AMD acceleration seems to be working.

I know that AMD has something called "Eyefinity" that handles running more than two monitors but I don't understand how to implement it.

Thanks very much in advance for anyone's time, attention and assistance.

Jordan

 

[Edhawk]

You have installed an older AMD card from the HD7000 series, which was released January 2012. Are you really surprised that the AMD card is not working as well as the Nvidia card released in September 2014.

Here is a screenshot from TechPowerUp site showing the difference between the HD7950 and GTX 970:


GTX 970 is rated as being 183% compared to the HD7950's 100%. That is a huge difference in capabilities.

I assume you still have one monitor connected to a mDP port, the Wacom Cintiq Pro connected to the second mDP port and the second monitor connected to the DVI port.

Are you using an 'Active' adapter to convert the mDP signal to DVI or HDMI connection on the monitor?

Which adapter are you using?

Definition of an Active adapter - An active DisplayPort adapter converts both single-mode and dual-mode output, so your connected video sources don't have to support DP++. The adapter performs the conversion from DisplayPort to VGA, DVI or HDMI instead of the source device.

You should not be using the adapter to connect to a VGA port on the monitor, as VGA connectors are not supported in macOS.


CUDA:
The Cuda drivers will do absolutely nothing for your AMD HD7950 card. Remove them. They have nothing to do with the ability to use multiple monitors. Even while you were using the Nvidia card they had nothing to do with your multi monitor setup.


Eyefinity:
You can not use the AMD Window app for 'EyeFinity', which is part of AMD's Windows drivers. There is no macOS alternative. You have to use the AMD drivers provided in macOS.


Clover & drivers:
The EmuVariableUefi-64.efi driver only affects/works with the Clover bootloader. This bootloader driver has absolutely no bearing or effect on how macOS runs once the OS takes control of the system.

The fact you are using this driver tells me you are using an old version of Clover, pre-r4896. As all versions released after this version dropped the use of the '-64' part of the name as all drivers were 64bit.

You are also probably still using the /CLOVER/drivers64 and /CLOVER/drivers64UEFI folders. These have been superseded in the newer versions of Clover by the /CLOVER/drivers/BIOS and /CLOVER/drivers/UEFI folders.

 

[JordanOrlando]

You have installed an older AMD card from the HD7000 series, which was released January 2012. Are you really surprised that the AMD card is not working as well as the Nvidia card released in September 2014.

Here is a screenshot from TechPowerUp site showing the difference between the HD7950 and GTX 970:

View attachment 525579
GTX 970 is rated as being 183% compared to the HD7950's 100%. That is a huge difference in capabilities.

I assume you still have one monitor connected to a mDP port, the Wacom Cintiq Pro connected to the second mDP port and the second monitor connected to the DVI port.

Are you using an 'Active' adapter to convert the mDP signal to DVI or HDMI connection on the monitor?

Which adapter are you using?

Definition of an Active adapter - An active DisplayPort adapter converts both single-mode and dual-mode output, so your connected video sources don't have to support DP++. The adapter performs the conversion from DisplayPort to VGA, DVI or HDMI instead of the source device.

You should not be using the adapter to connect to a VGA port on the monitor, as VGA connectors are not supported in macOS.


CUDA:
The Cuda drivers will do absolutely nothing for your AMD HD7950 card. Remove them. They have nothing to do with the ability to use multiple monitors. Even while you were using the Nvidia card they had nothing to do with your multi monitor setup.


Eyefinity:
You can not use the AMD Window app for 'EyeFinity', which is part of AMD's Windows drivers. There is no macOS alternative. You have to use the AMD drivers provided in macOS.


Clover & drivers:
The EmuVariableUefi-64.efi driver only affects/works with the Clover bootloader. This bootloader driver has absolutely no bearing or effect on how macOS runs once the OS takes control of the system.

The fact you are using this driver tells me you are using an old version of Clover, pre-r4896. As all versions released after this version dropped the use of the '-64' part of the name as all drivers were 64bit.

You are also probably still using the /CLOVER/drivers64 and /CLOVER/drivers64UEFI folders. These have been superseded in the newer versions of Clover by the /CLOVER/drivers/BIOS and /CLOVER/drivers/UEFI folders.

Thanks for responding. Obviously I bought the wrong (used) card — I was working from a list of Big Sur compatible cards on the OpenCore website, trying to find something reasonably priced — since I want to upgrade to Big Sir — and stupidly found a Sapphire that's older than the nVidia I was using, as you say.

Thanks for explaining about CUDA, Eyefinity etc. Once I realized that I've (as you explained) taken a step backwards in horsepower, it all made sense — I was assuming that I had to clear a driver/OS hurdle.

I guess I'll have to get a better card. Can you recommend a sub-brand or vintage of AMD card that will allow three monitors and provide reasonable hardware acceleration (for FCPX, After Effects etc.) equalling or exceeding what I was getting from the nVidia card, that won't break the bank?

Thanks for your advice/assistance and thanks again for responding.

Jordan

 

[Edhawk]

You may struggle getting hold of a decent AMD card that can run three displays for a reasonable cost.

I would think the RX580 or better should be able to provide what you need. The Vega series would be better, but at a cost/premium.

I use two Dell U1525H 2560x1440 displays (using two of the DP connectors) from my PowerColor Red Devil RX580. This card has 3 x DP, 1 x HDMI and 1 x DVI connectors. While is it not on the recommended list, it has been a good GPU for the last few years.

My GTX 780Ti is probably on a par with your GTX 970, plus it is compatible with macOS Catalina and Big Sur, possibly Monterey. This card has 2 x DVI, 1 x HDMI and 1 x DisplayPort connectors. A second hand GTX 780Ti might provide what you need. Again I have not tried to connect three displays to the GTX 780Ti just two different Dell Ultrasharp displays, when using it in one of my other hacks.

This screenshot from the TechPowerUp site shows the GTX 970, GTX 780 TI and the RX580 are all within around 10-13% of each other. The HD7990 and RX480 also fall within this group. Do not look at the GTX 690, this is a dual GPU card, but only one GPU works in macOS. The GTX 1060 is like the GTX 970 and not compatible with macOS.



The Radeon R9 390X card might be another option, but make sure it is the 'X' variant of the card. The non 'X' R9 390 cards are not as easy to get working in macOS. They do work but take more effort to get them working well.

 

[JordanOrlando]

You may struggle getting hold of a decent AMD card that can run three displays for a reasonable cost.

I would think the RX580 or better should be able to provide what you need. The Vega series would be better, but at a cost/premium.

I use two Dell U1525H 2560x1440 displays (using two of the DP connectors) from my PowerColor Red Devil RX580. This card has 3 x DP, 1 x HDMI and 1 x DVI connectors. While is it not on the recommended list, it has been a good GPU for the last few years.

My GTX 780Ti is probably on a par with your GTX 970, plus it is compatible with macOS Catalina and Big Sur, possibly Monterey. This card has 2 x DVI, 1 x HDMI and 1 x DisplayPort connectors. A second hand GTX 780Ti might provide what you need. Again I have not tried to connect three displays to the GTX 780Ti just two different Dell Ultrasharp displays, when using it in one of my other hacks.

This screenshot from the TechPowerUp site shows the GTX 970, GTX 780 TI and the RX580 are all within around 10-13% of each other. The HD7990 and RX480 also fall within this group. Do not look at the GTX 690, this is a dual GPU card, but only one GPU works in macOS. The GTX 1060 is like the GTX 970 and not compatible with macOS.

View attachment 525612

The Radeon R9 390X card might be another option, but make sure it is the 'X' variant of the card. The non 'X' R9 390 cards are not as easy to get working in macOS. They do work but take more effort to get them working well.

That's all extremely helpful — thank you very much.

In the end, three monitors may not be as important as sufficient After Effects/FCPX acceleration...but I'm sure those two strengths go hand in hand.

 

[Edhawk]

Some AMD cards can out perform more powerful Nvidia cards, when used in a real Mac or a Hack. It all depends on what you are trying to do and the software/codecs/processes you are using.

You need to give the HD7950 a try with just one monitor and the Wacom Cintiq connected, while using DaVinci Resolve to see if it is any good.