For 5K support, you must connect both Display Port connectors to one 5K display monitor. That is to say, two DisplayPort 1.2 cables must be connected from our dock to a single 5K display to support 5K@60Hz.

Note:

DisplayPort equipped monitors and DisplayPort cable must support DisplayPort 1.2 specification in order to support 4K@60Hz. The resolution will be limited to 4K@30Hz if the display or cable does not support DisplayPort 1.2 specifications.