Guys I’ve figured out a hacky but simple solution for making the 2075 8kx work with the 7900 xtx 
I’ve written it here: reddit link but I’ll repeat it for convenience:
tested with my 2075 model, v1.12 pimax play app (Pimax Client v1.12), a fresh install of Windows 11, latest amd driver
I flew around in VTOL VR and the experience was flawless.
how to consistently start up your pimax 8kx with a 7900xtx
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at the default 90hz setting, when you launch the pimax app, the hmd displays wont power on, just stay completely black
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go to the “device settings” menu and set the refresh rate to something other than 90hz, aka 75 or 60
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when you do this, the amd driver will crash and you wont be able to open the “device settings” menu again
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shut down the pimax app (in the desktop tray right click the pimax icon and click exit, just X-ing the app window wont shut it down)
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unplug the usb power cable (the thick one, the thinner usb cable and the dp cable can stay plugged in at all times)
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go to the “device settings” menu again, at this point its empty and says “device disconnected”
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plug the power cable back in
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wait until the options in the “device settings” menu come back
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click on the 90hz option
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the hmd restarts, the displays turn on and should work until you exit the pimax app again
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rinse and repeat the next time you want to play
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(optional) go and buy an usb hub with a power switch and an usb extension cable so you can plug the power cable in the front of the pc, and with the power switch you save the trouble of having to plug/unplug the cable a million times and make the connection loose