I'm using a Ryzen 9 9950X3D Linux workstation and only need basic display output, not gaming. The integrated graphics cannot run both of my monitors at their maximum refresh rates, so I added an RX 6500 XT.
The monitors are a BenQ RD280UG at 3840×2560 and 120 Hz, connected through HDMI 2.1, and an LG 27GR93U at 3840×2160 and 144 Hz, connected through DisplayPort 1.4 with DSC. Both monitors and cables should support those connections.
When the LG is already running at 3840×2160 and 144 Hz, the BenQ produces no image. Trying to enable it with xrandr at any resolution fails with "Configure crtc 0 failed." Is this a limitation of the RX 6500 XT, its display pipeline, DSC support, or the Linux driver? What graphics card would be a better, reasonably priced choice for driving these two displays without gaming features being the main concern?
3 Answers
The first thing to verify is the total display bandwidth, not just whether the card has HDMI 2.1 and DisplayPort 1.4. Two high-resolution, high-refresh displays—especially one running 4K/144 with DSC and the other at 3840×2560/120—can run into limits in the card’s display controllers or Linux driver even when the connector specifications look sufficient. Try both monitors at 120 Hz, then test each one separately and together at 60 Hz. Those combinations should help show whether this is bandwidth, DSC, or a driver issue.
The RX 6500 XT is a poor fit for this particular display setup. It is an entry-level gaming card, and its display-output capabilities and multi-monitor behavior may not be enough for two unusual high-resolution, high-refresh modes under Linux. Before replacing it, check whether both screens work at lower refresh rates, such as 120 Hz or 60 Hz, and look at the kernel and graphics-driver logs when xrandr reports the CRTC error.
If it turns out the card is the limitation, a newer card with stronger display-controller support would be a better choice, even if gaming performance is irrelevant. Compare the manufacturer’s supported simultaneous resolutions and refresh rates rather than only counting HDMI and DisplayPort versions.
The integrated graphics may be adequate for one monitor but not for both at these modes. With only one display connected, the other may be limited to roughly 95 Hz, which suggests the platform or available display bandwidth is already close to its limit. Testing one monitor at a time, then both at matching 120 Hz, is a useful way to isolate the problem.
The cables came with the monitors, and I prefer using the high refresh rates even for normal desktop work. I assumed HDMI 2.1 plus DP 1.4 with DSC would be enough, but I haven’t checked the RX 6500 XT’s detailed multi-display limits yet.