I have a mid 2010 MacPro that has had some video problems ever since I got it. I am trying to determine if it is a cable problem or some problem with the video card. I have a monitor connected via the DVI port and this has no problems. I have my TV connected via a minidisplayport with a MDP to HDMI adapter to HDMI cat 5 extender. This is what is giving me problems. Swapping out all this will cost over $100 so I would like to confirm that it is not a hardware issue with the computer if possible. I run the TV as a second monitor ans when I first set it up at the beginning of the year it would intermittently not detect the TV. I fiddled with things and removed some HTPC programs that were throwing a lot of things to the console logs. I finally got it working just fine for about 2 months. Now all of a sudden it will not always detect the TV. What I need to do to get it working again is to unplug the MDP plug and wait about 15-20 seconds then carefully plug it back in. It may take several times but eventually it will work. Just fiddling with the cables does nothing. There are times I get video but either no audio or audio with a lot of electronic distortion. The only way to fix this is to restart the computer. I am using XBMC as my HTPC software. What is new now is when I am watching a recording the video will go black and the audio will stop for 15-30 sec then the video comes back but no audio for another 15-20 seconds. I can rewind the recording to before it happened and watch with no problem through that section so i don't think it is a corrupted file. I have looked through console logs but I have no idea what I am looking for if there is a hardware issue. Any thoughts on how to determine if it is a video card issue before I start changing all the wires to the TV? One though I did have was to get a MDP to DVI adapter and connect my monitor to the other MDP port. If it is a MDP port problem then is should happen with both the monitor and the TV.