The HDMI Group suggests the following for HDMI cables over 10 meters long:
You indicated that you run yours at 20 meters. This may be the source of the problem.
Source: HDMI.org http://www.hdmi.org/learningcenter/faq.aspx
I own a 40'' samsung LCD TV.
I connected it to my computer via HDMI cable (20 meters)
My Video card is Asus 9800 GTX+ with 2 DVI out.Drivers are 182.50
My O.S. is Windows Vista Home Premium all updates done.
My problem is: My PC sometimes recognizes my TV, sometimes not. I tried everything. Reconnecting cables, restarting both TV and PC.
For 3 days I cant get anything from my TV. THere is no problem with my HD cable Tv OR PS3.