Took me for my Mac mini cable. I have a big 21: 9 screen reproduces at full resolution 2560x1080. Had the Mac mini connected only with HDMI. The resolution was grottig. Upscaled 1920x1080. Looked bad. Since the Mac mini HDMI out has a Thunderbolt port and can be connected to this a Mini DisplayPort cable, I decided for this cable. The prerequisite is of course that the screen also supports Diplayport.