2010 mac pro running catalina, this is a setup has been working until the latest update, now Zwift randomly crashes the computer during a ride, the screen goes black and the computer is unreponsive until I turn it off and back on. All other software works properly. I reinstalled Zwift and got the same result.
Can you share hardware specs for the machine? Is OS version 10.14.4?
What GPU is being used? What Firmware version have you got?
Which Opencore derivative are you using? OCLP, Martin Lo’s package, etc?
Nothing overheating?
You can use iStat menus to see the temps of everything. Keep a watch on the Northbridge temperature, especially if your 5,1 Mac Pro (2010-2012) is a dual CPU unit, the northbridge runs very hot on those machines (60ºC+, up to 75-80ºC). The push-pins that hold the heatsink on the northbridge are a known failure point, over time the plastic pins break. And the thermal paste can get old. The northbridge on the single CPU versions runs much cooler, even with the quickest X5690 Xeon CPU (6 core 3.46ghz).
That same caution note applies to the CPUs, the thermal paste for those will eventually need to be replaced.
Provided you’ve set your machine correctly, it should be possible for you to upgrade to MacOS Monterey using the right OpenCore package.
I have two 2010 Mac Pros (genuine 5,1, not 4,1) and a lot of experience with them in fully upgraded form.