That monitor does 3.840x1.200 which is far beyond what the the single link DVI on the Mini could handle.

Not sure if thats still the case but way back it was that if a monitor requested DualLink DVI (or in this case a higher bitrate as it lacks DVI) on a single link GFX card things would fail.

If you get it running with ASiegels tip you might try to create a 30Hz mode.

On the X5000 you would need a GFX card that can handle 4k over HDMI or DP, Dual-DVI will do you no good. Nor sure if those high bitrates are supported by CGX........

Edit:

Another tipp from the old days, delete any freshly made up monitor definition and put a known working (FullHD) file in there but I'm not sure how that would work today (it did work like a charm back in the 2.x days).

[ Edited by Kronos 01.11.2020 - 20:57 ]