Pro Display XDR momentarily looses connection to Mac Pro 2019

Redbeard3469 I see you had something very similar with momentary XDR blackouts, reported in this thread:

Apple Pro Display XDR goes black intermit… - Apple Community

Did you ever get this resolved and if so what was determined to be the problem? Mac Pro, Video Card, IO card, USB-C cable? XDR?

This post seems more about waking up the XDR after the display went to sleep. That isn't my issue. Nevertheless, I did try the tip offer: https://forums.macrumors.com/threads/waking-xdr-display-from-sleep.2221681/

Powered down the Mac Pro, unplugged every wire including the power cable. Held down the Power button about a minute. Plugged everything back in and powered up.

However this time, I only connected the XDR USB-C, and the Mac Pro power cable. The only other devices are connected via logitech Bluetooth keyboard and a Apple bluetooth Mouse.

First thing this morning before I had touched the Mac for several hours overnight, I heard the iPad power restored chime sound, so I knew this issue was still happening...

Next, I will try connecting the XDR to one of the top Mac Pro USB-C ports to try to determine if the IO build on the back is the problem...

I never thought of unplugging the power cable on the XDR. I'll try that also.

Someone else on a different forum also suggested these problems started for them when they plugged the XDR power into a UPS. I did that also this year. I checked the AC Voltage and it measured just slightly below the expected 120V in the USA. It measured 118.5 - 119.5v. I do not think that meets the threshold for a voltage sag but it is on my radar. The UPS is an APC BackUPS 900 fwiw.

Ok, the problem is now pointing at the Mac Pro, NOT the XDR.

I brought the whole kit to the Apple Store Genius Bar. The Genius decided based on description to take the XDR in for a 48 hour 'observation'. He told me there is NO hardware diagnostic tests they can run on the XDR. (so it puzzles me why they took it in).

Over the last two XDR-less days, I've been running the Mac Pro with bluetooth logitech keyboard and bluetooth Apple mouse...and my older 30" ACD plugged into the Mac Pro via a two adapters: ACD to Apple's DVI-D to Thunderbolt and then a 3rd part Thunderbolt to USC-C DisplayPort. I've had success with this string of adapters for some time now.

Anyway, the ACD has blacked out at least once per day that I've noticed and only very momentarily (like the XDR did). This time I ran sudo sysdiagnose almost immediately after it happened, AND, I had enabled Console app ahead of time to be streaming logs (and there are MANY MANY logs). I hope this capture will help me to get this sorted...

Meanwhile I've learned I can reinstall macOS without having to wipe my own data...I will also try that next.

yes, AMD Radeon Pro 580X 8 GB.

The Mac Pro has the IO board on the back with 2 USC-C and two USB-A and an 1/8" audio jack. The top of the Mac Pro has two additional USB-C. I believe all these are actually Thunderbolt (3) ports. I've tried the XDR in bot the IO card as well as the top USB-C ports as well as the ACD. Seems to happen on rear and top.

It looks like the AMD Radeon Pro 580X has two HDMI ports, just above the Ethernet ports on the rear. Unfortunately both my Pro Display XDR and the daisy-chained-adapters on my old Apple Cinema Display 30" all terminate with USB-C interfaces, not HDMI.

I just finished re-installing macOS...only it upgraded me to Sequoia 15.2 (instead of 15.1.1). I will find out soon if these glitches go away.... as I said, the Mac Pro hardware tests all passed.

Was able to capture logs from Console.app streaming live just before and during the blackout. I can see kernel errors and WindowServer errors. I've also submitted a sysdiagnose to bugreport.apple.com