Nasty, there was in no way that I said "did you try HDMI?" in my post. And if you're not going to provide any help, then maybe you shouldn't post. Because it's really cool that people like to tell me "did you read the damn post?" Like how you conveniently didn't read OP's post in another topic and suggested to do something he already did.ANYWAY
Well the only indication I could find about PCM audio on your receiver's manual which would be the most compatible format is that in fixed mode it only supports 2 channels (http://www.intl.onkyo.com/downloads/man ... nual_e.pdf
page 44). Even though somewhere else I found it supports 5.1/7.1 PCM audio.
Also go make sure in Control Panel -> Sound that the HDMI out supports surround sound formats. You can check this by right clicking on the item and going to its properties. Either way, if it's Dolby or DTS that are the only surround sound outputs, you're SOL as games don't use this.