After seeing the benchmarks for the new Mac Pro I've come to the conclusion that my souped up Mac Pro 5,1 is more than enough for my current needs, at least for another year or so. The Apple XDR however would provide me with great value for the money since it is so accurate. Is there any way to run the Apple XDR display with the 5,1? I have a Radeon VII and if I could use it with that display I would be set. So before I drop $5000 on the monitor I figured I would ask the Mac Rumors community. Any help is appreciated.
I just wanted to share my recent experience hooking up the new Apple XDR display with a mid-2010 Mac Pro 5,1. It does work, and quite a bit more easily than I expected from what I had read. I'm only getting 4K resolution and no easy way to control it, but I am enjoying the incredible contrast ratio, color palette and size.
My intention is to upgrade my Mac Pro (after a personal record of 10 years) to the new one some time soon. My machine has the 6 core Xeon processor running at 3.33GHz with 32MB of RAM. I have OSX 10.14.3 (Mojave). When I upgraded to Mojave, I was forced to upgrade the GPU to the Sapphire Radeon RX 580 with 8MB of RAM to support Metal. I've been using a very nice NEC Multisync PA271W monitor for years now, mostly to do photo editing (not professionally, but high end medium format with large files).
I saw the XDR display at my local store in Seattle and was amazed by the image quality. Because I had heard it was on backorder, I ordered one before I purchased the new Mac Pro. To my surprise, it was delivered in about 2-3 weeks. I haven't ordered the new Mac Pro yet, because some of the options (specifically for graphics) are listed as "coming soon" with no specified release date. The base GPU looks okay, but I think that the Radeon W5700x may give me more options later at a somewhat reasonable price point. So I decided to wait on ordering and try to use the monitor with my old machine.
After looking at a lot of videos and forum posts, it looked like the best route to hook up a Thunderbolt 3 monitor was to get a T3 PCIe card. I purchased the recommended Gigabyte Titan Ridge card (Rev 1) for about $100. As a note, it comes with the required Displayport to miniDisplayport cables that you need, so don't order them separately like I did. I installed the card directly above the graphics card, although it's not a perfect fit. The Titan Ridge is fairly thick and the fan blades of the Sapphire GPU rub a bit on the bottom. I placed a tiny plastic spacer (one of the Displayport caps) between the two to make the clearance. Because it's working, I haven't moved the card to another PCI slot, which would probably be the right solution.
Because I'm not powering anything through the card or running any USB devices, I didn't hook anything into the power connector ports or the USB connector. Based on a tiny photo I saw of someone with a similar setup, I did plug in the THB_C header cable and placed a jumper wire from pins 3 to 5. This apparently keep the card "awake" during boot up and allows it to be recognized. I haven't pulled the jumper out to test if it works without it. You don't need to do it through the cable, but it was easier to handle after installation and would allow for easier changes if needed. You could put the jumper wire directly into the port if you wanted. The two Displayport outputs from the Sapphire card then go directly into the Titan Ridge miniDisplayport inputs. In the following images, you can see the jumper on the header cable. You can also see the Displayport cables going from the doubleslot graphics card (just below the white connector going to the NEC monitor) to the Titan Ridge above. The Thunderbolt braided cable to the XDR is just to the left of the miniDisplayport inputs.
Once it was in place, I started up Windows 10 in a virtual machine using VMware Fusion. To my surprise, it did not require using Bootcamp. This was fortunate, because I never set up a Bootcamp partition and it might not be possible at this point for my setup (Bootcamp assistant won't run). I first downloaded the drivers from Gigabyte's website. I then realized that there was a disc that came with the card. I ran the setup program and everything happened automatically.
Here was the most shocking moment. Not expecting anything to happen yet (Windows and OSX still running without reboot), I plugged the XDR monitor into the card and it immediately came on and my computer switch to dual display mode. OMG! Even more amazing, it continues to work even with Windows completely closed and doing a cold reboot of OSX alone. I've never had to boot Windows again to get it to work. I had read that this was a necessary kluge to make it work and that there may be instability. So far, this has not been the case. The XDR display is acknowledged in the "About this Mac" summary with the proper name and icon, indicating that it recognized in Mojave (not just Catalina). As I mentioned, I'm getting 4K resolution (3840x2160), but it looks great compared to my NEC. I also can't adjust things like brightness (as far as I can tell) but it looks like I can select a color profile. There have been the occasional quirks of changes in which monitor is the primary and which side is right and left. But those are minor issues.
In summary, for about $100 I found a way to use the new XDR monitor with my old Mac Pro that is perfectly satisfactory until I decide to upgrade the machine. There may be things that could be done differently (like which PCI slot is used, the jumper wire), but I'm not messing with what worked. As a disclaimer, I'm not a tech guy, but a reasonably tech savvy consumer that was looking for a solution for a problem that had not been explicitly outlined on the net so far. I hope that my experience helps other people.