I've got a HTPC with a Radeon 5450 conn ected to the TV via HDMI. The HTPC displays perfectly, but when the PC is on, I get no signal on my TV. When I turn the PC off or unplug the HDMI cable between the PC and TV, the signal comes back.
I've tried using a DVI to HDMI cable, outputting DVA from the video card to HDMI on the TV and that doesn't interfere with the TV at all, but of course then I can't output audio
The issue definitely seems to be related to the HDMI output of the graphics card - any ideas?
Sounds like something in your computer or plugged into your computer is putting electrical feedback through the tv to the cable. Here are a few things you can try though if you have a tv tuner in the computer its likely that. Make sure the cable isnt pluged into the tv tuner in the computer before continuing. If it clears up when you unplug the cable going into the computer then its the TV tuner in the computer.
Unplug everything from your computer besides the power and the HDMI cord. Check reception. If still poor then unplug everything from the electrical outlet (surge protector) besides the computer, and the tv and cable. If reception is still poor then plug directely into the wall for a quick check. If still poor then use a different outlet. If it is still poor its time to move onto the hardware in the computer itself.
If it clears up at anytime when you unplug something then thats the issue. Something is not grouding properly.
what kind of tv do you watch? set top box or straight coax? if it's set top box, do you have it connected via hdmi as well or composites? if by composites, you may have it connected to same input assignment as the PC and the HDMI will try to override the analog signal.
i don't know too much about tvs and antenna reception, are you in USA using Digital over the air? or somewhere else?
it could be the simple fact that there is too much interference from the HDMI connector when it is active for the signal to get through,, does it do this for any other HDMI connection?
since we're talking old school, if you used a VCR on the coax connection, does same issue happen when you turn on the PC? could be something is just wrong with your TV --- sometimes it is difficult to diagnose the actual problem without spending some money, but finding a workaround is usually free
to be honest, you may want to just get a TV tuner for your PC and watch TV through your PC on WMC as you can then get an online guide,, I prefer XBMC over WMC any day, however XBMC doesn't support Live TV right now and I have to admit Windows media center is a pretty slick setup for TV without a digital box.