What distro are you using? I've been using multi-monitor setups for years, and it works with zero configuration on Ubuntu and Debian.

With more than 1 (high end) video card?

Graphic performance is excellent if you don't insist on say using Nvidia hardware with the open source Nouveau drivers everyone knows sucks. Open source AMD and closed source Nvidia both provide good performance.

Going with just US figures the average spent on a computer in 2020 is 632 usd total. A high end card on the other hand is $400 to $800 each. a 2000-3000 pc with 800-1600 in graphics hardware is probably somewhat up there in the 99th percentile of configurations its pretty niche even so I cannot imagine any even technical challenges whatsoever with all the monitors hooked to the same GPU whereas a high end card ought to support 3 monitors.

So now are we talking about a 2000-3000 dollar pc with 2 dedicated GPUS with 4+ monitors?

Brief research seems to suggest this is challenging. Improving it would also seem not to benefit many users. Even talking merely about windows gamers only 1% used crossfire or sli.

There is even a plausible solution for people who want lots of displays so long as they are ok with a single gpu.

Although supporting 2 to 3 monitors is incredibly common there are actually cards which support 4-6.

For example

https://www.newegg.com/asrock-radeon-rx-5700-xt-rx-5700-xt-t...

There is probably no good solution for multiple GPUs + multiple displays because virtually nobody uses it now and longer term it seems even less will.

The logical decision is to go with the strongest single GPU with enough outputs for the monitors you plan to drive.

I appreciate you proving my point. High end desktops are not viable on Linux, which is a shame, because I really wanted it to work.

I give you a variety of points and all I get back is a single flip quip. This is a disappointing rejoinder.

You CAN have a high end desktop. You can even have 3-6 monitors if it makes you happy. The only thing you cannot do is plug your monitors into the outputs of both GPUs. You must purchase GPUs wherein a single GPU has sufficient outputs and let the secondary GPU serve to aid in your favorite GPU compute or game playing adventure.

For example

https://www.newegg.com/gigabyte-radeon-rx-vega-64-gv-rxvega6...

This supports 6 displays and crossfire so it plays well with lots of displays and multiple GPU.

Stepping up further in price

https://www.newegg.com/evga-geforce-rtx-2080-super-08g-p4-32...

Supports 4 displays and SLI

Is it possible to have two cards and have the second card do computations for the first one to render? I would have thought the time it took to move the data would make that hard.

Generally one actually runs games on one monitor in the first place so this is the only way it even could work. Work can be divided up by frame for example.

Crossfire and SLI rely on a high speed interconnect and game specific support.

Dual GPU is a much smaller niche than "high end desktops".

Multiple gpus are even supported just not outputs hooked up to both GPUs as a single X screen.

https://wiki.archlinux.org/index.php/NVIDIA/Tips_and_tricks#...