I am in a similar situation.
I have 3 Dell U2311H and two 290s and a Denon AVR-X1000 as Audio system.
I run two monitors via DVI cable and the third from HDMI to Denon and there i use a HDMI->DVI Adapter to the 3rd Monitor.
I've had a hole lot of problems about my Monitor going into sleep and receiver turning off and when you wake the Computer in this Moment the Passtrough kicks in and sends the signal over the offline Receiver, meaning you have another EDID signal than when the Receiver is Online causen the Eyefinity Setup to break up, or the Monitor to turn on/off every 3-5 seconds.
Even after powering on the receiver he Audio did not get recognised and the monitor kept turning on and off.
The Solution to this problem was something like unpliging the HDMI cable on the GPU, restarting both devices, and sometimes pluging the hdmi back while running windows solved it.
Now after a few firmware updates from Denon and after i deactivated the "powersave" features (aka turn off after 60 minutes idle) i don't have this problems anymore.
Nillaz wrote:
Honestly, if your MB has an optical out you might be better served by just running a TOSLINK cable from the PC to the receiver for audio and keep the monitor hooked to your PC directly.
Hell no, 7.1 Channel 24bit 192khz signal straight over HDMI all the way!
Toslink only supports 2 channels PCM, if you want 7.1 you need dts dolby or some other compression stuff.