Well, my integrated GPU has a hard time with external 5k screens on Windows fairly often. I need to manually install the Intel drivers, which work for a while, but then Windows helpfully updates them to the earlier, borked version.

At least now this sometimes works if I turn the laptop on with the screen plugged-in. If I go to the toilet and the screen turns off, it's back to some low resolution. When my computer was new 5 years ago, it never did work in 5k, so... baby steps, right?.

Worked perfectly OOB on Linux.