I'm running Vista SP1 onboard Gigabyte AMD 780G graphics (HD3200). The onboard graphics is connected either by HDMI -> HDMI or HDMI -> DVI Adaptar -> DVI to my 1080 Samsung LCD. When I turn on the computer with the LCD attached there are no problems. However if I switch my TV off or switch to another source, when i switch back to the HTPC i get a no signal error. I have spent a long time researching this on google. Apparently when the TV switches off or to another source it sends a signal to the HTPC letting the computer know it has turned off/switched source. This enables the HTPC to power down the graphics card to save power. When the TV is switched back on it doesn't send a proper EDID signal to wake up the graphics card on the HTPC. Apparently lots of people have these problems and apparently updating all the drivers etc does not help the problem. I can also confirm that adjusting the power saving features in Vista also doesn't fix the problem. The only solution that i have found is.
(1) unplug the HDMI cable for a few minutes then replug it into either the HDMI or the DVI (via adaptor).
(2) Apparently assigning a short cut key to change the screen res to different res and then back again will get the graphics to start working again
(3) Turning the HTPC off and then on
(4) Installing a "DVI Detective" cable. Basically this is a little adaptor that you can program with the EDID signal of your monitor, once programmed it automatically continuously sends EDID information so the HTPC never knows that the monitor has been switched off. If you google "DVI detective" you can find a lot of information on this issue.
Just wondering if other people in the forum have this problem, and if so what solution do they use? I'm thinking of order the DVI Detective, it will cost about $120-$130 NZD including postage on ebay.