Previous HDMI versions use three data channels (each operating at up to 6.0GHz in HDMI 2.0, or up to 3.4GHz in HDMI 1.4), with an additional channel for the TMDS clock signal, which runs at a fraction of the data channel speed (one tenth the speed, or up to 340MHz, for signaling rates up to 3.4GHz; one fortieth the speed, or up to 150MHz, for signaling rates between 3.4 and 6.0GHz).