A common question we hear is, “What is the maximum HDMI cable length that you recommend?”
HDMI is a very complex communication protocol and there are many factors involved in determining whether “long” cable lengths will work or not. HDMI.org specifies the required performance of a cable but does not specify a maximum cable length. The use of “High Speed” cables (referred to as Category 2 cables in the HDMI specification) is recommended. High Speed cables are tested to perform at speeds that can handle the bandwidth requirements necessary for all current HDMI specifications. HDMI.org recommends using a repeater if your cable length exceeds 10 meters.
With any long run of an HDMI cable, quality manufactured cables can play a significant role in successfully running HDMI over such longer distances.
For more information, please go to http://www.hdmi.org/learningcenter/faq.aspx#44