RE: HDMI Output only detects 2 channels not 5.1
it's a limitation of my motherboard
Sorry but I did not explain it too good. It is not a limitation of the motherboard. I meant that the Realtek codec probably is only a 2 channel codec, however that doesn't have anything to do with the HDMI audio. HDMI audio is a raw digital signal, which does not pass through the Realtek's DAC. It goes straight to an external DAC, usually one built into a TV. In your case, you are using the DAC of your digital receiver.
If the receiver is receiving the signal and is producing any audio, then it is working. Whether or not you are getting surround sound depends on the setup of the receiver, and whether your signal source is a surround source. What I mean is that if you are playing a stereo audio file, it is only going to come out of 2 speakers.
I don't know what you have to do to set up your receiver. The FAQ explains the steps and the order of the steps to setup HDMI with a TV, but I don't have any instructions like that for a receiver. Also, if you read the FAQ, you have updated or re-installed your Intel graphics driver.