I have tried the CAC-1331 with my Acer XV273K display and Radeon RX 580 (using CAC-2068 cable).
The CAC-1331 can do 4096×2304 but some timings cause a problem. For example, the native timing of the 21.5″ LG UltraFine 4K display does not work through the CAC-1331 even though the XV273K can accept the timing from HDMI 2.0 or DisplayPort.
4096x2[email protected] 142.198kHz 593.82MHz h(8 32 40 +) v(1 8 57 -) 16:9
Some CVT-RB timings for 4096×2304 do work (50Hz, 51Hz, 53Hz, 57Hz, 58Hz) but some do not (52Hz, 54Hz, etc.)
Some timings have the wrong colors (3840×2160 594MHz has wrong colors but 3840×2160 at 533MHz is good).
I could not get any 5120×1440, 5120×2160, or 5120×2880 timings to work even with refresh rate set as low as 30Hz.
Kind of disappointing. I would expect any timing to work as long as the pixel clock is 600 MHz or less (the limit of HDMI 2.0 at 8 bpc and no chroma sub sampling). It would be cool if it could support higher pixel clock with chroma sub sampling (for example, 4:2:0 can do 1200 MHz with 8 bpc; DisplayPort 1.2 is limited to 4:2:2 which can do 1080 MHz at 8 bpc – good enough for 5K 60Hz).