My motherboard is a Biostar TZ77a and I have two eVGA 7870s in crossfire. Crossfire is enabled and I can play games easily on my primary samsung monitor. The main issue that I'm having is my secondary use of this machine is for watching movies via HDMI to my Panasonic Plasma.
With my laptop (6990m) this was super easy to plug in the laptop to my Onkyo SR818 receiver and pass through video and audio to my TV and have surround sound. With the desktop I just built with crossfire I cannot have it work. With the 7870s this has not work and I have tried old drivers, current drivers, and beta drivers and used the AMD removal utility with reboots between versions to clean them out.
Here's what normally happens...
I have been able to get the video to work by connecting the PC directly to the TV but no audio.
If I hook the HDMI from PC directly up to the Onkyo, I get a blue screen with no video input (unplugging the HDMI flickers and goes back to a No Signal screen) indicating a signal is there but the Onkyo is not able to process it correctly. I have tried multiple HDMI inputs on the receiver and have had a PS3, Xbox, DTV, and Blu ray player hooked up to it with no issues.
I have tried disabling the HDMI control on my receiver for the TV and disabling the audio return settings to make it the most basic HDMI passthrough setup and it makes no difference.
The audio control panel always shows the 7870 audio devices as being unplugged no matter if I hook up to the TV directly or through the Onkyo Receiver.
My audio option is always defaulted to the SPDIF of the onboard Realtek. I see no way to disable the onboard audio in the BIOS for this board so I have tried disabling it through the device manager which disables it but the AMD Radeon audio devices still all show as unplugged.
Both Audio and Video:
Most of the time I have to have the TV plugged into the top video card next to the DVI port where my Monitor is always plugged in otherwise it won't detect the display as being connected. Even when detected, I get no video. This is with Crossfire enabled. Only a few times have I been able to plug the TV into the HDMI port of the bottom of the card and been able to detect the TV and show video but still never any audio.
I have tried multiple and even brand new HDMI cables.