MP 1,1-5,1 Dual video

[WayneStewart]

I have a 5,1. I need to be able to run 10.6. I’d like to be able to run 10.14. Seems like all the video cards work with one but not the other. So an idea struck me. If I installed both cards and just connected the appropriate one to a monitor. Would that work. Would my Mac think there are 2 displays?

 

[tsialex]

I have a 5,1. I need to be able to run 10.6. I’d like to be able to run 10.14. Seems like all the video cards work with one but not the other. So an idea struck me. If I installed both cards and just connected the appropriate one to a monitor. Would that work. Would my Mac think there are 2 displays?

Up to 10.13, this kinda work more or less fine with a GT120 + GTX 680 and some other compatible GPUs, but with 10.14 all sort of weird problems happen when you have one unsupported GPU and a supported one. AFAIK, lots of people tried this scenario and no one got it working acceptably.

If you don't need GPU acceleration with Snow Leopard, you can use a Mac Edition GPU or a flashed GPU and boot 10.6. It would be un-accelerated and lots of display resolutions wouldn't work at all, but would be enough for some applications.

Another way to try is to virtualise 10.6, with Parallels or VMware Fusion, GPU would not be a problem at all if you don't have to use some interface that only work with bare metal.

Theoretically:

If you use OpenCore, you can disable a PCIe slot and then you could have two GPUs installed, but just one working and the unsupported one wouldn't be seen by macOS. It's a complex setup to do, you would have to make different OC configurations for 10.6 and 10.14, but if I'd really need this, would be the way I try.

 

[startergo]

I tried this with my dual setup in OC:

<dict>
    <key>DeviceProperties</key>
    <dict>
        <key>Add</key>
        <dict>
            <key>PciRoot(0x0)/Pci(0x3,0x0)/Pci(0x0,0x0)</key>
            <dict>
                <key>IOName</key>
                <string>#display</string>
                <key>class-code</key>
                <data>
                /////w==
                </data>
                <key>name</key>
                <data>
                I2Rpc3BsYXk=
                </data>
                <key>rebuild-device-tree</key>
                <data>
                AA==
                </data>
            </dict>
        </dict>
        <key>Delete</key>
        <dict>
            <key>PciRoot(0x0)/Pci(0x3,0x0)/Pci(0x0,0x0)</key>
            <array>
                <string>name</string>
                <string>IOName</string>
                <string>class-code</string>
            </array>
        </dict>
    </dict>
</dict>

Now I only see one display:

 

[WayneStewart]

Something just occurred to me. I’ve got a PCIe expansion box. It’s huge with 20 PCIe slots. I’ve been using it with a couple of NVMe SSDs and a few other cards. Now I’m thinking that maybe I can put one video card in there. When I acquired the expansion box it came with what the seller called a parts machine. I never tried it but doesn’t look damaged. It may be that it was called a parts machine is because they only had one host card. The cable that comes with the expansion boxes are easy to plug and unplug.

 

[startergo]

Something just occurred to me. I’ve got a PCIe expansion box. It’s huge with 20 PCIe slots. I’ve been using it with a couple of NVMe SSDs and a few other cards. Now I’m thinking that maybe I can put one video card in there. When I acquired the expansion box it came with what the seller called a parts machine. I never tried it but doesn’t look damaged. It may be that it was called a parts machine is because they only had one host card. The cable that comes with the expansion boxes are easy to plug and unplug.

I am using 5 pcie slot expansion board. My second card is there.