MP 7,1 4K Monitor Support

[mossman1120]

I have a 2019 MacPro with stock W5700X MPU and an after market RX 6900 XT. I recently got a new monitor U3225QE and I am trying to figure out if I can use the included Thunderbolt 4 cable (I know I only have Thunderbolt 3) to connect (video + data) or if I need a USB-C style connector that goes to DisplayPort for video + USB for data? I am also curious if I would only get 60 Hz refresh rate or 120 Hz. Any help would be greatly appreciated! Thanks 🙂

 

[mattspace]

What GPU are you going to use for display, and what happens when you try to connect it?

 

[mossman1120]

What GPU are you going to use for display, and what happens when you try to connect it?

I don't have it yet though I would like to use the RX 6900 XT since it is "better card". Trying to plan ahead to make sure I have the right cables.

 

[mattspace]

either connection option should work, though some TB4 displays have come out that don't work on TB3.

Does the 6900 have Type-c connectors? Because that's unlikely to be thunderbolt, and the TB ports on your mac are only going to do video from the 5700.

 

[mossman1120]

either connection option should work, though some TB4 displays have come out that don't wok on TB3.

Does the 6900 have Type-c connectors? Because that's unlikely to be thunderbolt, and the TB ports on your mac are only going to do video from the 5700.

Well that would be disappointing. I was looking forward to not having to run both a video and a data cable to the monitor.

I am not sure about the 6900, when I look in System Information I see the following for the display currently plugged into it:

Chipset Model: AMD Radeon RX 6900 XT
Type: GPU
Bus: PCIe
Slot: Slot-3
PCIe Lane Width: x16
VRAM (Total): 16 GB
Vendor: AMD (0x1002)
Device ID: 0x73bf
Revision ID: 0x00c0
ROM Revision: 113-D4120100-100
Metal Support: Metal 3
Displays:
DELL U3014:
    Resolution: 2560 x 1600
    UI Looks like: 2560 x 1600 @ 60.00Hz
    Framebuffer Depth: 30-Bit Color (ARGB2101010)
    Display Serial Number:
    Main Display: Yes
    Mirror: Off
    Online: Yes
    Rotation: Supported
    Connection Type: Thunderbolt/DisplayPort

So I am not sure. The full model of the card is: GIGABYTE AMD Radeon RX 6900XT 16GB Reference.

Do you know if it will support 120 Hz or only 60 Hz?

 

[SDAVE]

I have a 2019 MacPro with stock W5700X MPU and an after market RX 6900 XT. I recently got a new monitor U3225QE and I am trying to figure out if I can use the included Thunderbolt 4 cable (I know I only have Thunderbolt 3) to connect (video + data) or if I need a USB-C style connector that goes to DisplayPort for video + USB for data? I am also curious if I would only get 60 Hz refresh rate or 120 Hz. Any help would be greatly appreciated! Thanks 🙂

If you have a Thunderbolt cable, they are higher quality that pass through more data, so this will work. Cheaper USB-C cables won't.

There is a USB-C connection on the 6900XT (it is not Thunderbolt) and if you connect that to a non-Thunderbolt display (even a Thunderbolt display) it will pass through video in USB-C Alt mode (basically a DisplayPort signal wrapped on USB-C) and will pass through Video + Audio (4k and higher will be fine) and 120Hz will be fine as well.

So short answer is: Yes it will work with a Thunderbolt cable (it won't run as Thunderbolt tho) but the cable will work.

Your alternative is getting a DisplayPort (6900xt) > DisplayPort (monitor) cable and connecting a Thynderbolt cable to the back of the Mac Pro to enable your hub functionality (hopefully it supports it).

So main point is your monitor supports Thunderbolt as a Hub + Monitor, so the 6900XT USB-C does not support Thunderbolt (for that you need an MPX card as it does Thunderbolt video passthrough).

Now, if you truly want a single cable solution you can try this:

WJESOG DisplayPort to USB C Cable

Displayport to USB C Cable 6.6ft 4K@60Hz

a.co

However, your Hub will work at USB2.0 speeds unfortunately, but you should get all the USB functionalities out of your monitor + full hi-res video support. This is a similar cable im using for years on my Dual Studio Displays + 6900XT (at 5k60hz).

 

[mossman1120]

If you have a Thunderbolt cable, they are higher quality that pass through more data, so this will work. Cheaper USB-C cables won't.

There is a USB-C connection on the 6900XT (it is not Thunderbolt) and if you connect that to a non-Thunderbolt display (even a Thunderbolt display) it will pass through video in USB-C Alt mode (basically a DisplayPort signal wrapped on USB-C) and will pass through Video + Audio (4k and higher will be fine) and 120Hz will be fine as well.

So short answer is: Yes it will work with a Thunderbolt cable (it won't run as Thunderbolt tho) but the cable will work.

Your alternative is getting a DisplayPort (6900xt) > DisplayPort (monitor) cable and connecting a Thynderbolt cable to the back of the Mac Pro to enable your hub functionality (hopefully it supports it).

So main point is your monitor supports Thunderbolt as a Hub + Monitor, so the 6900XT USB-C does not support Thunderbolt (for that you need an MPX card as it does Thunderbolt video passthrough).

Now, if you truly want a single cable solution you can try this:

WJESOG DisplayPort to USB C Cable

Displayport to USB C Cable 6.6ft 4K@60Hz

a.co

However, your Hub will work at USB2.0 speeds unfortunately, but you should get all the USB functionalities out of your monitor + full hi-res video support. This is a similar cable im using for years on my Dual Studio Displays + 6900XT (at 5k60hz).

Ah okay so since the 6900XT isn't in a MPX module I don't get Thunderbolt, just video. So if I use the ports on my MPX graphic card in theory I should be able to use a single Thunderbolt cable for both video and data. If I use the 6900XT then I would need two cables, one from the 6900XT for video and then another from the MacPro for data?

Thanks for the callout on the cable. I have a couple of spare USB ports on the MacPro so if I have to use two cables it isn't the end of the world.

How are you able to get data out of your 6900XT?

 

[mattspace]

So if I use the ports on my MPX graphic card in theory I should be able to use a single Thunderbolt cable for both video and data. If I use the 6900XT then I would need two cables, one from the 6900XT for video and then another from the MacPro for data?

Your W5700X has 1x HDMI, and 4x Thunderbolt 3. They are normal Thunderbolt ports - you can plug hard drives, docks, etc. into them.

 

[SDAVE]

Ah okay so since the 6900XT isn't in a MPX module I don't get Thunderbolt, just video. So if I use the ports on my MPX graphic card in theory I should be able to use a single Thunderbolt cable for both video and data. If I use the 6900XT then I would need two cables, one from the 6900XT for video and then another from the MacPro for data?

Thanks for the callout on the cable. I have a couple of spare USB ports on the MacPro so if I have to use two cables it isn't the end of the world.

How are you able to get data out of your 6900XT?

You will get Video + Audio from the 6900XT USB-C port. The video will run through USB-C Alt mode (DisplayPort video). However for some reason audio doesn't come out of the USBC port under macOS with the 6900XT, probably related to the lack of audio drivers in macOS, since it works fine in Windows. You also won't get data out of it, which is why a single cable going to a Studio Display doesn't allow you to use the displays special features like Webcam, monitor control (brightness/audio), display speakers, USBC hub, or anything related to Thunderbolt.

The workaround is the cable I provided. It passes DisplayPort data into the monitor via USBC and the extra USB cable allows you to also use the built in monitor features. You connect the DisplayPort + USB cable to the Mac Pro and the USBC end to the monitor. The only downside here as mentioned is that the data feature will be limited to USB2.0 so if your hub on the monitor is USB3.0 it will run slower. I personally don't care, I don't connect fast devices on the dual studio display hubs, I just connect things like DACs, USB mice receivers and a microphone. For anything faster like an SSD (Thunderbolt or USBC) I just connect directly to the Mac.

You will just need 1 of these cables if you have 1 of these monitors. 2 if you have 2 of them (like I have with dual Studio Displays). If you don't care about the hub, monitor speakers, monitor display controls etc, you can just run DisplayPort (6900XT) > Displayport (monitor) and get a video signal with no issues. But your hub and other things won't work.

A single Thunderbolt (or USBC) cable can run a lot of different types of data inside of it, that's why people get confused. You just have to find a workaround for what you're trying to do.

If you have a MPX card, no issues. If you have a MacBook Pro, no issues. If you have a Mac Studio, no issues. A single Thunderbolt cable will take care of everything, but not in your case since you have an OEM 6900XT. The card was not designed for a Mac, but it works because macOS has drivers for it.

I personally use the Belkin version of this cable (2 of them) and have for years with no issues. I heard the one I sent previously works just as good but haven't personally tested. The Belkin cable used to be $60 you should be able to find it as well if you want to spend that much. I can definitely tell you that the Belkin one works since I use it daily. It has 2 USB cables vs 1 in the one I sent, so not sure what the difference is. I guess have to try it, Amazon has a good return policy.

 

[SDAVE]

Your W5700X has 1x HDMI, and 4x Thunderbolt 3. They are normal Thunderbolt ports - you can plug hard drives, docks, etc. into them.

The Thunderbolt ports on the MPX GPU cards also provide video + data passthrough on top of just being regular Thunderbolt port. This is not possible with non MPX module cards like the OEM 6900XT. This is why you can run a Studio Display with a single Thunderbolt cable and get all the features without workarounds like the one I provided.

 

[mossman1120]

You will get Video + Audio from the 6900XT USB-C port. The video will run through USB-C Alt mode (DisplayPort video). However for some reason audio doesn't come out of the USBC port under macOS with the 6900XT, probably related to the lack of audio drivers in macOS, since it works fine in Windows. You also won't get data out of it, which is why a single cable going to a Studio Display doesn't allow you to use the displays special features like Webcam, monitor control (brightness/audio), display speakers, USBC hub, or anything related to Thunderbolt.

The workaround is the cable I provided. It passes DisplayPort data into the monitor via USBC and the extra USB cable allows you to also use the built in monitor features. You connect the DisplayPort + USB cable to the Mac Pro and the USBC end to the monitor. The only downside here as mentioned is that the data feature will be limited to USB2.0 so if your hub on the monitor is USB3.0 it will run slower. I personally don't care, I don't connect fast devices on the dual studio display hubs, I just connect things like DACs, USB mice receivers and a microphone. For anything faster like an SSD (Thunderbolt or USBC) I just connect directly to the Mac.

You will just need 1 of these cables if you have 1 of these monitors. 2 if you have 2 of them (like I have with dual Studio Displays). If you don't care about the hub, monitor speakers, monitor display controls etc, you can just run DisplayPort (6900XT) > Displayport (monitor) and get a video signal with no issues. But your hub and other things won't work.

A single Thunderbolt (or USBC) cable can run a lot of different types of data inside of it, that's why people get confused. You just have to find a workaround for what you're trying to do.

If you have a MPX card, no issues. If you have a MacBook Pro, no issues. If you have a Mac Studio, no issues. A single Thunderbolt cable will take care of everything, but not in your case since you have an OEM 6900XT. The card was not designed for a Mac, but it works because macOS has drivers for it.

I personally use the Belkin version of this cable (2 of them) and have for years with no issues. I heard the one I sent previously works just as good but haven't personally tested. The Belkin cable used to be $60 you should be able to find it as well if you want to spend that much. I can definitely tell you that the Belkin one works since I use it daily. It has 2 USB cables vs 1 in the one I sent, so not sure what the difference is. I guess have to try it, Amazon has a good return policy.

I wonder why they don't make a USB 3 version of that cable.

 

[SDAVE]

I wonder why they don't make a USB 3 version of that cable.

Niche market

 

[mattspace]

The Thunderbolt ports on the MPX GPU cards also provide video + data passthrough on top of just being regular Thunderbolt port.

How is that different from the IO card, or Top case TB ports?

 

[SDAVE]

How is that different from the IO card, or Top case TB ports?

No different, as long as you have an MPX GPU. If you don't have any MPX GPUs in the system and for example a single 6900XT like I do, none of the Thunderbolt ports will route video (top of case, IO card) or audio. Apple routes Video+Audio through custom chips on the logic board when there's an MPX GPU module. To work around this, you must use the workaround I described if you want full functionality, or else you will only get video and audio through the DisplayPort on a non MPX GPU.

 

[mattspace]

No different, as long as you have an MPX GPU. If you don't have any MPX GPUs in the system and for example a single 6900XT like I do, none of the Thunderbolt ports will route video (top of case, IO card) or audio. Apple routes Video+Audio through custom chips on the logic board when there's an MPX GPU module. To work around this, you must use the workaround I described if you want full functionality, or else you will only get video and audio through the DisplayPort on a non MPX GPU.

Right, but in OPs case he has the W5700X in place, so all his TB ports are carrying video from it, *if* he wants to use that GPU for driving displays.

 

[SDAVE]

Right, but in OPs case he has the W5700X in place, so all his TB ports are carrying video from it, *if* he wants to use that GPU for driving displays.

OP won't get the performance they want by using the W5700X output. The 6900XT is just going to sit idle since it won't be used as an output device. If they're using an app that can assign the GPU to the 6900XT maybe.

Even if you have the W5700X, the 6900XT won't get Thunderbolt video out. I've tried it. I have a 580X in the closet and haven't touched it in years.

I recommend completely removing the W5700X and just using the 6900XT and the cable.

BTW why do you have to be contrarian to all the responses to my posts? lol
I'll probably stop posting here soon as well.

 

[mattspace]

OP won't get the performance they want by using the W5700X output. The 6900XT is just going to sit idle since it won't be used as an output device. If they're using an app that can assign the GPU to the 6900XT maybe.

Even if you have the W5700X, the 6900XT won't get Thunderbolt video out. I've tried it. I have a 580X in the closet and haven't touched it in years.

I recommend completely removing the W5700X and just using the 6900XT and the cable.

BTW why do you have to be contrarian to all the responses to my posts? lol
I'll probably stop posting here soon as well.

i'm not being contrarian, I'm trying to clarify where you were suggesting the relationship between video out, and thunderbolt sits.

It's a ridiculously confusing setup because what he has on his 6900XT is a Type-C *USB* port, that does displayport Alt mode which should support DP 2.0/2.1 (from memory). I'm hazy though on whether a Type-C USB port can do video and data on the one cable and one port, when connecting to a TB display, or does it handshake to Video only as a DP connection. As compared to a display with a Type-C USB (non Thunderbolt) port?

His Type-C Thunderbolt ports (with the W5700X plugged in) will support a Thunderbolt connection to a display, or a DP 1.4 alt mode connection.

Something to also bear in mind, plugging the USB end of that cable into your Mac - if you're out of USB ports, using a TB to USB A adapter will engage 4 extra PCI lanes for that.

On top of that we have the bigger issue, it's a TB4 display, and a number of TB4 displays won't handshake as TB devices with TB3 macs (and potentially not do video on a straight TB cable as a result).

His W5700X can support 6 displays, the 6900XT only 4. It would be really good to know what software he's using, because a lot of apps will just farm compute out to non-display GPUs, so performance can be less important for the one you have the display connected to.

 

[SDAVE]

i'm not being contrarian, I'm trying to clarify where you were suggesting the relationship between video out, and thunderbolt sits.

It's a ridiculously confusing setup because what he has on his 6900XT is a Type-C *USB* port, that does displayport Alt mode which should support DP 2.0/2.1 (from memory). I'm hazy though on whether a Type-C USB port can do video and data on the one cable and one port, when connecting to a TB display, or does it handshake to Video only as a DP connection. As compared to a display with a Type-C USB (non Thunderbolt) port?

His Type-C Thunderbolt ports (with the W5700X plugged in) will support a Thunderbolt connection to a display, or a DP 1.4 alt mode connection.

Something to also bear in mind, plugging the USB end of that cable into your Mac - if you're out of USB ports, using a TB to USB A adapter will engage 4 extra PCI lanes for that.

On top of that we have the bigger issue, it's a TB4 display, and a number of TB4 displays won't handshake as TB devices with TB3 macs (and potentially not do video on a straight TB cable as a result).

His W5700X can support 6 displays, the 6900XT only 4. It would be really good to know what software he's using, because a lot of apps will just farm compute out to non-display GPUs, so performance can be less important for the one you have the display connected to.

Yeah, USBC is just a port at the end of the day. This whole situation feels like a Frankenstein and the only way to find out is if you try it first hand and confirm with other folks.

MPX gpu will support Thunderbolt protocols and other protocols that are part of the USBC specs (there's so many)

6900XT will only support USBC protocols like Alt mode. As mentioned the USBC port on 6900XT is kind of useless under macOS as there's no audio drivers for it, so you will only get Alt mode video out of it with a single USBC cable.

Doesn't make sense For OP to keep the W5700X in the system and use it as an output device. You will see a big jump in performance even day to day stuff on the 6900XT (a 6 year old gpu btw lol). But I assume OP bought the 6900XT to be able to use the powerful gpu for maybe gaming or 3d apps. Let's see what they say.

 

[mossman1120]

So I wanted to follow up.

I got the screens connected, one via USB-C <-> DP on the 6900XT, one via USB-C <-> DP on the W5700X using Bus A, and via Thunderbolt using Bus B. For the two monitors connected via USB-C <-> I used the upstream data link so that USB ports on the monitor wouldn't run at USB 2 speeds. The one connected via Thunderbolt established a 10 Gb/s link while the ones using my USB card only 5Bg/s but I suspect that is a an issue with my USB card being old or not using enough PCIe lanes.

At first things seemed okay but then I started to noticed a perceptible GUI lag especially when doing thing in the Finder. It is weird because I can watch a movie without issue but if I drag a window around or move the mouse back and forth over the DocK Icons it really starts to lag.

The other night I had some free time and I started to place Sins of the Solar Empire 2 via Crossover and during my game play the screen plugged into the 6900XT suddenly went dark and reported loss of signal. My mouse could move and I still had picture out of the other two screen but things seems to stopped refreshing and final the system went down with a kernel panic.

Upon reboot the system didn't see the 6900XT any more which made me thing the card had moved to the land beyond. I powered everything off for a few minutes and restart and the card showed back up again. I thought it might have had something to do with CrossOver so I decided to give it another try.

I was able to play for couple of hours and then the same thing happened. During this second attempt I was watching the reported temperature of both cards and the 6900XT was sitting around 160F and the W5700X around 140F.

I started to do some searching online and Google AI was saying there an issue running RDNA 1 and RDNA 2 cards with split monitors in OSX due to how it renders the WindowServer. It said that I should use either use the 6900XT or the W5700X exclusively and that would resolve the error. It said I could leave both cards in.

The justification it gave for this is:

When all three monitors are on the 6900 XT, macOS uses a feature called Single-GPU Framebuffer Management. The operating system no longer has to copy active 120Hz display textures across the motherboard's PCIe slots. The 8.3-millisecond synchronization window is no longer a bottleneck because the data never leaves the 6900 XT's internal high-speed memory bus. The code path that triggered the Watchdog Timeout is completely eliminated.

It suggested looking for the following in the crash reports:

If the log text shows strings like this:

• panic(cpu...): "skipping watchdog... Framebuffer hang"
• com.apple.kext.AMDRadeonX6000
• IOAccelerator or WindowServer

This is definitive, undeniable proof that your card is physically healthy. It tells you that the macOS display driver got stuck in an infinite timing loop trying to synchronize the 120Hz canvas between the W5700X and the 6900 XT over the motherboard lanes, timed out, and panicked to protect itself. Moving the cables to the 6900 XT permanently deletes this entire code pathway, fixing the issue.

Given that Apple sold a W6900X I check to see if they anything about not using mixed generation cards. I also tried to do some searching myself and really couldn't find anything conclusive about this.

I checked the Crash Report logs and saw the following:

Process: WindowServer [253]
Path: ???
Identifier: WindowServer
Version: ???
Code Type: 00000000 (Native)
Role: Unspecified
Parent Process: ??? [Unknown]
Coalition: <none> []
User ID:

Date/Time: 2026-07-05
Launch Time:
Hardware Model: MacPro7,1
OS Version: macOS 26.5.1 (25F80)
Release Type: User

riggered by Thread:
Triggered by Thread: Unknown

Exception Type:

Termination Reason: Namespace WATCHDOG, Code 1, monitoring timed out for service
(1 monitored services unresponsive): checkin with service: WindowServer (1 induced crashes) returned not alive with context:
unresponsive work processor(s): WindowServer main thread
80 seconds since last successful checkin, 702 total successful checkins since 7100 seconds ago, 39 seconds since last crashed by watchdogd, , has not exited since first loaded

This wasn't the exact wording for it seems a bit similar so I am curious is this just the standard AI Slop or if this is something people have run into.

After the second crash I moved all the monitors to the W5700X (2 in the card + 1 in the IO Card) so they each have their own bus to see the system acts. The 6900XT is connected and recognize but not being used for anything currently.

Update: 1
I did check Activity Monitor and although nothing is plugged into the card itself I do see a process called "Safari Graphics and Media" using the 6900XT. The total CPU time for the card is 1.05 compared to 19:25.09 for the W5700X. I am not sure if the system is trying to offload something behind the scenes still.

 

[reader50]

I've thought a graphics card was failing on me more than once. Only to find an active video adapter was at fault. If you encounter the problem again, you might check any active adapters plugged into your cards. One might be hot to the touch. And they're way cheaper to replace than graphics cards.

 

[SDAVE]

So I wanted to follow up.

I got the screens connected, one via USB-C <-> DP on the 6900XT, one via USB-C <-> DP on the W5700X using Bus A, and via Thunderbolt using Bus B. For the two monitors connected via USB-C <-> I used the upstream data link so that USB ports on the monitor wouldn't run at USB 2 speeds. The one connected via Thunderbolt established a 10 Gb/s link while the ones using my USB card only 5Bg/s but I suspect that is a an issue with my USB card being old or not using enough PCIe lanes.

At first things seemed okay but then I started to noticed a perceptible GUI lag especially when doing thing in the Finder. It is weird because I can watch a movie without issue but if I drag a window around or move the mouse back and forth over the DocK Icons it really starts to lag.

The other night I had some free time and I started to place Sins of the Solar Empire 2 via Crossover and during my game play the screen plugged into the 6900XT suddenly went dark and reported loss of signal. My mouse could move and I still had picture out of the other two screen but things seems to stopped refreshing and final the system went down with a kernel panic.

Upon reboot the system didn't see the 6900XT any more which made me thing the card had moved to the land beyond. I powered everything off for a few minutes and restart and the card showed back up again. I thought it might have had something to do with CrossOver so I decided to give it another try.

I was able to play for couple of hours and then the same thing happened. During this second attempt I was watching the reported temperature of both cards and the 6900XT was sitting around 160F and the W5700X around 140F.

I started to do some searching online and Google AI was saying there an issue running RDNA 1 and RDNA 2 cards with split monitors in OSX due to how it renders the WindowServer. It said that I should use either use the 6900XT or the W5700X exclusively and that would resolve the error. It said I could leave both cards in.

The justification it gave for this is:


It suggested looking for the following in the crash reports:


Given that Apple sold a W6900X I check to see if they anything about not using mixed generation cards. I also tried to do some searching myself and really couldn't find anything conclusive about this.

I checked the Crash Report logs and saw the following:


This wasn't the exact wording for it seems a bit similar so I am curious is this just the standard AI Slop or if this is something people have run into.

After the second crash I moved all the monitors to the W5700X (2 in the card + 1 in the IO Card) so they each have their own bus to see the system acts. The 6900XT is connected and recognize but not being used for anything currently.

Update: 1
I did check Activity Monitor and although nothing is plugged into the card itself I do see a process called "Safari Graphics and Media" using the 6900XT. The total CPU time for the card is 1.05 compared to 19:25.09 for the W5700X. I am not sure if the system is trying to offload something behind the scenes still.

Just completely remove W5700X, it's an underpowered card and it's conflicting with the 6900XT. Just keep the 6900XT.

You can get a DisplayPort → USBC (run via Alt mode) any thunderbolt display. I run dual 5k Apple Studio Displays (1st gen) via these cables. You don't necessarily need it if you don't care about USB functionality on the monitors, just get a DisplayPort → USBC adapter. Any modern one should do.

 

[mossman1120]

I've thought a graphics card was failing on me more than once. Only to find an active video adapter was at fault. If you encounter the problem again, you might check any active adapters plugged into your cards. One might be hot to the touch. And they're way cheaper to replace than graphics cards.

In the 6900XT I only have one USB-C <-> DP cable (6 foot) and in the W5700X I only have one Thunderbolt cable (3 foot) + one USB-C <-> DP (6 foot). All are passive as far as I know.

 

[mossman1120]

Just completely remove W5700X, it's an underpowered card and it's conflicting with the 6900XT. Just keep the 6900XT.

You can get a DisplayPort → USBC (run via Alt mode) any thunderbolt display. I run dual 5k Apple Studio Displays (1st gen) via these cables. You don't necessarily need it if you don't care about USB functionality on the monitors, just get a DisplayPort → USBC adapter. Any modern one should do.

The reference card I have has one HDMI, one USB-C, and two DP. I can use my existing USB-C <-> DP cable as well as two DP <-> cables that came with the monitor.

My understanding is that I pull the MPX module, I would lose thunderbolt from the IO Card and top ports?

I see you are running a 6900XT as well, what MPX module did you have? Did you pull it for a similar reason?

 

[mossman1120]

I wanted to follow up that at least for now I pulled the 6900XT as just launching a game in CrossOver cause the panic. Things seem to be stable for now. I was going slot the the 6900XT in a PC to check if needs a firearm update as well as run benchmark software to confirm the card isn't sad.

 

[SDAVE]

The reference card I have has one HDMI, one USB-C, and two DP. I can use my existing USB-C <-> DP cable as well as two DP <-> cables that came with the monitor.

My understanding is that I pull the MPX module, I would lose thunderbolt from the IO Card and top ports?

I see you are running a 6900XT as well, what MPX module did you have? Did you pull it for a similar reason?

Yes you will lose Thunderbolt VIDEO from the top and rear IO cards, but not regular Thunderbolt for data. Only MPX GPUs support Thunderbolt video from all ports if it's in the machine. The Intel 7,1 Mac Pro routes GPU video properly through all Thunderbolt ports if there is a MPX GPU in the machine. If there's no MPX GPU in there, Thunderbolt video is ignored on all ports.

Thunderbolt also supports USB-C DP Alt Mode which means that you can connect Thunderbolt monitors into a GPU that has a DisplayPort. The USBC port on the 6900XT also supports DP Alt Mode, but it will be for video only.

I had the 580X MPX and pulled that out a long time ago since it's a very slow GPU and for dual 5K monitors its not enough. I now just run the 6900XT to Apple Cinema Display 5k (dual) with no issues for years using that cable I provided a link to.

It is a known issue that if you have a MPX GPU and for example a 6900XT, the OS doesn't know exactly how to switch it around and to use what. You don't need to have the MPX GPU in your system at all, it's a waste of a slot + performance drop.

What monitor are you using btw? You have more than enough ports on the 6900XT and plenty of adapters to make this work. I am not sure why you're so stuck on the dated MPX GPU?