The HDMI connector on your motherboard supports only a very basic HDMI 1.4 connection. You should, in theory, be able to get a 4K@30Hz connection, but that's at best and the stars align. If they've implemented it properly on this motherboard, there should be a DisplayPort 1.2 connection available through the USB-C connector on the backplane. This would be capable of supporting 4K @ 60 Hz if it has been implemented properly. You would need a good USB-C-to-HDMI dongle to achieve this.