Hey Folks, Let me first stress that I have searched these forums and others extensively for possible solutions and have had not success, so thank you for your kind direction and troubleshooting guidelines in advance.
At my church we have a media computer that runs our projector (via hdmi over ethernet) and presentation software. For about a year it was running great off the Motherboards on board graphics HD 5000 series I believe. About 4 months ago we started getting flickering on the projector and the computer would sometimes crash.
I ordered a dedicated card, HD 7750 and a new stick of ram (which I determined was the cause of the crash). The Sunday before I put the card in we couldn't get the computer to recognize the computer at all. I installed the card and it worked great...but only for 2-3 weeks, at which point it stopped recognizing the projector. We could plug any other computer in and it would recognize the projector, but I could also plug other monitors on the tech desk into the media computer and it would instantly recognize it.
So in one case, it looks like the problem with the HDMI over ethernet, but the other indicates that it is the computer.
For the heck of it, I tried going back to the onboard card (no success) and reinstalled windows from scratch (which made it work for another 2 weeks and then back to the same issue), with no real success.