I presume that you have a PSU of at least 1100 Watts for two Air-Cooler Vega64 in Crossfire with three monitors attached.
From Microsoft concerning your Blue-screen Error: Bug Check 0xEA THREAD_STUCK_IN_DEVICE_DRIVER - Windows drivers | Microsoft Docs
A device driver is spinning in an infinite loop, most likely waiting for hardware to become idle.
This usually indicates problem with the hardware itself, or with the device driver programming the hardware incorrectly. Frequently, this is the result of a bad video card or a bad display driver.
I noticed your reply on my thread. I had some minimal success with using virtual resolution to set my lower Res monitor to 4k as well.
Are any of your monitors mirroring or are all 3 different? I usually experience this issue the worst when mirroring.
I still haven't "solved" it but I would definitely try using virtual resolution to set the 1440 to 4k which allowed me to change some settings. I ended up just setting all 3 to 1440p which allowed me to aggressively undervolt/overclock.
Good luck, keep me updated!