Five or six simultaneous displays from AMD GPU (eg 7970)?

[TheBloke]

I currently use an Nvidia 760 in my 10.13.3 Hack, with four monitors (one at 4K.) However I am considering replacing it with an AMD GPU, for two reasons:

1. I would like to add at least a fifth, maybe a sixth monitor
2. I get occasional lags and slowdowns with the 760, with both NVidiaWeb and Native drivers. It's a lot better than it was when I used a 980Ti, which is why I reverted to the 760, but it's still not perfectly smooth. Especially when having a full screen video playing and then activate screen animations like Swipe Left a Space and Mission Control.

NVidia GPUs are limited to max four displays at once, but AMD has EyeFinity which I believe allows use of all outputs at once.

I'm particularly looking at the ASUS HD 7970 DirectCU II 3GB which has six outputs (2xDVI, 4xDP). There's also a variety of 7970 cards with five outputs.

What I don't know for sure is whether I will definitely be able to use all five or six outputs, simultaneously, in a macOS Hack? I believe the OS definitely supports it (eg the late-2013 Mac Pro says it supports 'up to 6 Thunderbolt displays'), but I don't know if the GPU will in a Hackintosh system.

I've Googled a lot but can't find proof of anyone connecting more than four displays to an AMD Hack.

One person did tell me that it should be possible, but might require custom configuration to 'unlock' all the outputs?

If anyone knows for sure, I'd be most grateful for info before I buy a new GPU (which will require I sell my existing 760 as well.)

Thanks

TB

 

[MacPack]

Why don't you use two GPUs?

For the price of the Asus refurbed you could have something much more modern and power efficient. (In theory)

I know that RX 5XX cards can do 4k @ 60Hz over HDMI, HEVC encode and decode, and HDMI/DP audio.

I can't confirm if the DVI port is working on my card, but two RX 560 would be much cheaper

 

[TheBloke]

Yeah, that was actually my first thought. I thought I'd add a second NVidia card to my existing 760. There's a few issues though:

• I am using every single slot on my mobo except a single PCIe 2.0 x1 slot.
  • There is actually a Zotac NVidia 710 1GB card available on a PCIe 3.0 x1 slot for about £60, and I thought to get it to add to my 760.
    
  • But I haven't yet had confirmation that it will definitely work fine in a PCIe 2.0, not 3.0 slot. It seems it should be OK in principle, but the details of the card are a little unclear as to whether 3.0 is an absolute requirement; PCIe 2.0 x1 is not much bandwidth, and it's not impossible it simply wouldn't work at all without 3.0.
• I could free up another PCIe 2.0 x8 slot, for example by selling my 2 x 10GBe X520-DA1 cards and replacing with a dual-port X520-DA2. That way I could add any second GPU, but it is a bit of work and hassle.
  
• But then the next issue is the small desktop lags and stutters I get from NVidia cards, using either Native or Web drivers. That's getting a bit annoying, so I thought if I could go purely AMD, I would be solving two problems at once.
• Hence a single 7970 card looked like a perfect solution: it's AMD not NV; it's a direct replacement for my 760, no need to change any other cards to make room to use more slots; and it's got five or six outputs, so if I can use all of them on a single card, that'd be much neater.

Note that I'm only looking to spend about £150 on the replacement card -that's the cost of one 7970 3GB. The RX 560 are also about £150 each, so I couldn't afford two of them. I could get an RX 560 instead of a 7970, but a quick look at them suggests they don't have the 5-6 outputs of the 7970? They generally only seem to have three in fact.

Unless I sold my 980Ti as well. Which has crossed my mind. But I will want to play games again sometime in the future, so I don't really want to sell it and give up the ability to play games at 4K resolution in Windows.

If there was an AMD card that could do 4K games and that I could afford by selling my 980Ti, that would be another option to consider. But from what I've read in reviews/specs, there isn't - the 580 for example can't really game at 4K, and the Vega64 cards are stupid amounts of money, far more than I'd get from my 980Ti. Hence I thought to hold on to that 980Ti.

TLDR: if it can work with 5 or 6 displays, replacing the 760 with a 7970 seems to be the best solution: I get AMD not NVidia; I don't have to sell/replace other cards to free up more slots; I do a fairly like-for-like replacement in terms of desktop 3D capabilities without spending much money (I can sell the 760 for £100 and buy a 7970 for £140.)

 

[toleda]

AMD has EyeFinity which I believe allows use of all outputs at once.

Eyefinity, macOS supports 6 DP ports.

 

[TheBloke]

Eyefinity, macOS supports 6 DP ports.

So are you saying that with an AMD 7970, I can plug in six monitors and it will definitely just work out of the box? I can get six different pictures on six different screens (not just mirrored/stretched)?

You say 6 DP ports - the card I am looking at has 2 x DVI and 4 x DP, is that still fine?

If that's all correct then that is awesome. But I'd just like to be sure I'm understading 100% correctly.

Thanks very much!

One more question: I am a bit confused because the EyeFinity articles talk about DisplayPort being required. And you @toleda said "supports 6 DP ports".

I don't know if this means 6 screens only works if all screens are DisplayPort? And whether it matters if a DisplayPort to HDMI or DVI adapter is used (so a DP port is still used on the GPU, but the whole connection is not DP->DP.)

Only two of my monitors support DisplayPort. With the others I would use a DisplayPort to HDMI or DisplayPort to DVI adapter.

To be exact, if I connected five monitors on the ASUS 7970 card (which has 2xDVI + 4xDP), it would be like this:

1. DVI -> DVI (1920x1200)
   
2. DP -> DP (4K)
3. DP -> DP (1920x1200)
4. DP -> HDMI (1080p)
5. DP -> DVI (1920x1200)

Could you confirm this would work OK? I would be able to get a different picture on all five screens in macOS?

EDIT: no it wouldn't, but there's a solution; see next post.

 

[TheBloke]

Sorry for the multiple posts, but I think I have everything straightened out now:

• EyeFinity allows up to two "legacy" connections, which includes DVI and HDMI
• The other connections must be DP
• This means that with my current monitors, I could only run four displays: 1 x DVI, 1 x DVI->HDMI, 2 x DP.
• However, I can buy an "Active DP to HDMI" adapter, which specifically states it is treated like a DP connection, and that it is supported by EyeFinity. The description also states that "EyeFinity supports up to two adapters"
• This means I should be able to run the following configuration to support a full six monitors on an Asus 7970:
  • DVI -> DVI
  • DVI -> DVI
  • DP -> DP
  • DP -> DP
  • DP -> active adapter -> HDMI
  • DP -> active adapter -> HDMI
• In fact I only plan to use five screens, so I would use one adapter.
• As an aside, I believe it also works to do: DP -> active adapter -> HDMI -> passive cable/adapter -> DVI. Or there are active DP -> DVI adapters available from other manufacturers.

Phew! I am pretty confident that is all correct. Confident enough to buy the card.

Thanks

 

[joeblough]

FWIW i am using an eyefinity active DP->DVI adapter for my 2nd apple 30" monitor and it does work (HD560) however when waking from display sleep it is not showing the blurred-out desktop wallpaper but instead is (sort of) driving the real signal to the monitor. it's all psychedelic colors and blocky but live signal is there. if i cancel the login and then re-wake, the right thing is happening.

this is with SMBIOS 18,1 on a z370+i8770k.

 

[TheBloke]

OK thanks joe, that's good to know. I could always forego display sleep if need be.

Since I made my post yesterday I've realised things aren't quite as simple as I thought. I'm confident that Eyefinity with 6 displays works in principle.

What I'm no longer sure of is whether I can get a 7970 working with 6 active connections. I have done more research and learning, such as reading the Radeon Compatibility Guide here, and various other posts such as the Framebuffer patching guide and I realise now that there is no reference Framebuffer for the 7xxx cards that has 6 ports. There is Hamachi which has 4 ports: 2 x DP + HDMI + DVI.

In fact I can only see one FB that has 6+ ports, and it is for the 5xxx cards (Zonalis)

So I am still unclear whether I can use 2 x DVI + 4 x DP on a 7970 card, when there is no default Framebuffer that has this many ports? The patching guides I have read, eg carpentryplus25's guide, talk about "finding a FB with the right number of ports". Which I can't do. I can see from the patching guide that it's possible to change what a port is (eg change a DVI to DP if your card has DP in that position). I can't yet see if it's possible to add more ports.

This is what I am still stuck on - will my 7970 show all 6 ports (or at least 5) in macOS 10.13.3 or 10.13.4? I don't yet have an answer for that.

I am continuing to research on this.

 

[toleda]

unclear whether I can use 2 x DVI + 4 x DP on a 7970 card

Examples: macpro6,1/ManuroS and imac18,3/Florin use 6 DP connectors
No AMD7000Controller framebuffer is configured for 2 DVI and 4 DP
No AMD7000Controller 6 connector framebuffer has DVI
Several AMD7000Controller framebuffers are configured for 6 DP
One AMD7000Controller framebuffer is configured for 2 LVDS and 4 DP
One AMD7000Controller framebuffer is configured for 1 LVDS, 1 HDMI and 4 DP

Risk is no framebuffer patch works for 2 DVI and 4 DP

 

[TheBloke]

Thank you @toleda. Since my last post I had extracted the Framebuffer personalities and saw the ones configured for 6 DP and hoped I could patch them to 2 x DVI + 4 x DP. But as you say, this might prove a problem.

I have one last question: do you know if it will be possible to do the necessary connector patching on an AMD 7970, on an X58/LGA1366 system with only Legacy boot, and no iGPU/second GPU?

This is the last piece of the puzzle I cannot work out, and I am worried it will not work. For example WhateverGreen states it's meant for UEFI, and unknown for Legacy. carpentryplus25's Framebuffer patch guide says specifically UEFI only. Mieze's SSDT patching is unstated as to whether it's UEFI only, or also supports Legacy.

I have today ordered an Asus Matrix Platinum 7970 3GB, as I thought the best thing to do was buy a card and start playing around, rather than trying to work this out in theory only. The card will arrive on Wednesday or Thursday.

EDIT: I have since been told that the 7970 definitely should work in my system, as it's still natively supported by 10.13.

However I remain uncertain as to whether this also means I can patch the connectors to get the full 6, or whether the patching methods might still require UEFI (carpentryplus25's guide states UEFI required for his method, and WhateverGreen might also require UEFI.)