Thanks for the advice, I installed the Debian package “read-edid” and used the get-edid program from it to get the EDID from the monitor. Then I installed the “wxedid” package to display it graphically because the parse-edid program from read-edid didn’t work well. According to wxedid there’s a seletion of 38402160 modes and some 40962160 modes. So it seems that the EDID is the problem.

DSC is designed to be visually lossless not mathematically lossless - you could say the same about JPEG. There are many reports about text being rendered badly with DSC.

MAXSUN Intel Arc B580 Milestone 12G Graphics Card (MS-ARC-B580-MILESTONE-12G

The above is the cheapest card from my local store that has DisplayPort 2.1 (the rest have 1.4). It’s $469 compared to $199 for a RX 6400 or RX 6500. I can probably find somewhere cheaper to buy these things but I’m working on the assumption that the ratios of prices are going to be about the same.

From the Wikipedia page it looks like DSC is needed to do 8K@60Hz on DisplayPort 1.4. I think that is bad for text though.

That card has DisplayPort 1.4 which means that if HDMI doesn’t work then it’s limited to HBR3 which gives 24bpp@31Hz, which is barely adequate.

Also how do you set the bpp rates? The DisplayPort wikipedia page says that 24bpp and 30bpp are supported, but how do I even know which is in use?

The TV has built in NetFlix and YouTube so I don’t have much need for playing video from Linux. Currently YouTube is the only source of 8K video that I’m aware of.

I know it’s low end, I just don’t want to spend much money. It seems likely that one way or another I’ll find some problem with whatever card I get and want to replace it in a couple of years so I don’t want to spend much.

The card is documented as having HDMI 2.1.

For my home workstation running Debian/Bookworm I started running Wayland-Plasma when Xorg mysteriously refused to work after replacing my video card. Wayland just worked and really had no issues for me so while I’m sure I could have solved the X11 problem I didn’t have a real need to.

I also changed my laptop to Wayland-Plasma more recently. A problem I had was in setting up the right modes for external monitors on laptops but that seems to work OK now. Generally things just work.