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I want to use my ATI Radeon 4850 to output Multichannel PCM sound to my Onkyo TX-SR805 Receiver and get a full screen picture on my Dell 2405FPW with 1920x1200.
I want to use this setup + a projector in home theather applications later but first I want to get it working for every day use.
So I don't care for dts-HD, Dolby true HD or HDCP in the first step.

My plan was to use a hdmi-splitter to get the signal to monitor, receiver and projector, but I encountered several problems.
  • If the EDID information of the monitor are used I cannot enable sound as the card thinks there is no sound capable device connected.
  • If the EDID information of the receiver is used I cannot use 1920x1200 as the receiver reports 1920x1200 as maximum resolution.
  • If I plugin the monitor in output port of the receiver the maximum resolution is still limited to 1080p and what makes this setup completly unusable is the fact, that this only works as long as the receiver is set to the correct input.
So I took some time reading the forum I figured out I have to use the DVI-HDMI dongle that came with my card and my monitor has to be detected as a DTV in the control panel and I have to provide an extension block in the EDID information providing the sound capabilities.
I bought some resistor and IC and build myself a little circuit which connectes the DDC wires to my own eeprom.

Now I can setup sound and maximum resolution the way I want, but I don't get neither sound nor a picture in Windows (XP or Vista doesn't matter).
The monitor tells me that he cannot display this mode and the receiver just says no signal, even if I enter
But I get a picture while booting so all data channels should be correct and reading the EDID information also works.
In case you are wondering, I use a second monitor to setup.
What can do. Is there a difference between the output, when the ATI-card is in HDMI mode?