Funny

I have 6 monitors running through 2 very different GPUs on KDE right now, on the PC I'm using to type this. Works great, and I suspect I could add more monitors and more GPUs with no issues.

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Okay, granted, there actually are some issues. My issues:

• It seems to depend on the distro. Kubuntu and Ubuntu Studio have been able to do it just fine, automatically configuring it correctly from the first boot; no other distro I've tried to date was able to make it work, regardless of how much I screwed around with things. All other distros I tried would only ever display through one GPU at a time; they could never use both simultaneously.

• Using two very different GPUs is maybe necessary for it to work? Using two nvidia GPUs (1070 & 3090) didn't work -- it would only ever output from one GPU or the other. Using two Radeon cards also didn't work. But an nvidia 3090 and an old Radeon together? They both work perfectly, and are able to drive displays independently. (4 displays on the 3090, 2 on the old Radeon.) My motherboard doesn't have integrated graphics, so I wasn't able to test that. (Though it has more than 4 ports, the 3090 is only capable of driving 4 independent displays at a time, which seems to be a universal hardware limitation, hence the need for a second GPU.)

• The system becomes unbootable (boots to a blank black screen) anytime GPU drivers are updated. That one really burned me the first couple times. The solution is to just not update the GPU drivers. sudo apt hold *nvidia* did the trick. (Yeah, I know that's not ideal. But it works.)

But now that I've got the kinks worked out, it has been running flawlessly for me for years. Absolutely insane setup, including very different displays, different resolutions, different refresh rates, but it chugs along just fine and just kind of magically works.