Display flickering, need help spliting HDMI signal

Hello, I am pretty decent with computers but not an expert. I am having a little trouble with my home theater PC display flickering. My video card is a Radeon HD 6900 and the drivers are up to date. I have the HDMI out of my PC going to an Onkyo 7.1ch HT-R590 receiver and it's output going to my LG 42" TV. My OS is Windows 7 Ultimate X64.

The system used to work perfectly fine but over time the display started to flicker at random times. I tried to hook my PC directly to my TV and it works perfectly fine, so I am 100% certain the problem is in the receiver. I did a bit of research and it appears to be a problem with my receiver over heating. I placed a 120mm fan on top which helped some but the problem is still there.

Now, if I run my HDMI to my TV, I cannot use 7.1ch surround sound. (Even after playing with Audio Return Channel) If I run optical to the receiver, my video card only puts out 5.1ch surround sound for some weird reason. So I did the next obvious choice, I ran a DVI to HDMI to my TV for video and HDMI to my receiver for audio. I thought it would trick it into thinking there was two displays but this does not work, I do not get audio.

I was wondering if you guys knew of any utilities that would allow me to output audio on one HDMI stream and video on my DVI port. I did a lot of looking around and it looks like DMCA calls for HDMI to be encrypted and you can't separate the stream. Or would I just be better off getting a separate audio card to connect to my a/v receiver?

Thanks!

I have cleaned it out, there wasn't much dust in to begin with. Sending the a/v rx in for repair is a last ditch effort for me. It's just a PITA.

Just use the optical cable. There is no such thing as 7.1 yet. The 2 other channels are pulled from the 5.1 source. Do you have a playstation or a blueray player running through the receiver ? If so do they function properly ?