I read up a fair bit on how to port video from my Mac Pro to my HDTV, and I have created the following setup, which is supposed to work: • Mac Pro 1,1 made in Nov 2007, OS 10.6.8, true Apple certified Radeon 5700 (with jumper power cable installed internally), 4GB RAM • A temporary crummy 15" Dell monitor connected to the DVI port • This Mini DisplayPort to HDMI Adapter Cable in the mini displayport on the 5700 card: http://www.amazon.com/gp/product/B003BERYLA/ref=oh_details_o00_s00_i01?ie=UTF8&psc=1 • This 30' HDMI cable running from the above adaptor to my Samsung UN40EH5050 LED HDTV, HDMI/DVI port 1 in: http://www.amazon.com/gp/product/B0027NTUMC/ref=oh_details_o00_s00_i03?ie=UTF8&psc=1 I turn both the TV and Mac off, turn on the TV with Source to the HDMI/DVI port, then boot the Mac. The TV stays black, and System Profiler / Displays show no recognition of another display device at all. The same thing happens even if I unplug the Dell monitor before booting the Mac Pro. I also tried it with a 3' HDMI cable with the same result, so the issue is not cable length. What is the problem? What is the solution? Thank you for helping.