I'm looking for a solution on the HDMI-Output problem for a couple of month now and wasn't able to fix it till now. Allmost tried every suggestion I found in Intel's communities or from other forums by Google searching!
For me it's important to get my 2nd monitor working back again, but it looks like I have to buy another computer with an external GPU that doesn't have those issues. Can't really believe, that Intel isn't able to provide their customers with a fix on an issue that is known for over a year now.
So here are my informations on what happened to my system:
I'm running an ACER Aspire Z5700 All-In-One Desktop with an Intel I5 660 CPU actually, which I have changed from the I3 550 CPU, because I thought it may fix the issue, but it doesn't. Have bought the system around 2 years ago and all was working fine. Then I decided to work with a 2nd monitor and took an ACER X223W for that, had to connect over HDMI -> DVI because monitor only has VGA and DVI-Input and the AIO has only one HDMI-Output. But that wasn't a problem, all was working fine, got signal on 2nd monitor, could change between clone or extended, had no problems while powering off/on, all worked like a charm, till I disconnected the HDMI-Cable one time for using the 2nd monitor to configure another computer. After this was done, I tried to reconnect to my AIO and the trouble begun. On my 2nd monitor I only got a black screen with a short "no signal" message, that monitor falls back to power-safe!
OK, what's going wrong now I asked myself, why the hell will no signal found. I tried to get a signal again with a rollback, nothing changed. I tried all available drivers, from Acer Support and all of the Intel drivers. I have updated the BIOS to latest and downgraded it, I bought new cables and adapters, nothing worked. Then I bought the I5 660 CPU around 3 weeks ago to give it a try but same result. Last thing I could do, was to format and try with a fresh install. F***, had to backup around 650 GB files, but I tried and horray nothing worked at all.
So, now we come to the part, that makes me sure, that it isn't a Windows 7 issue, it is definitive an Intel driver issue, because if I take same HDMI-cable, adapter and monitor and connect it to my son's computer, also running Windows 7 but with external GPU, then all is working fine again. Tested with an LCD-TV too, on my AIO no signal, on my son's computer it worked.
Of cause, now we could think the HDMI-Output-Port might not work, but I can't believe that, cause when either the 2nd monitor or LCD-TV is connected, they will shown in device manager, in Intels Control Panel and in Windows Control.
Here are some screens:
DxDiag and ICP-Diag are attached.
Maybe I got blind over all the time with trying to fix the issue, but I really don't know what else I could do or how to solve it, so I'll give it away to you with the hope someone may help me.
Sorry for my english, it isn't my native language, tried my best to describe all I had done.