All SPDIF, TOSLINK, HDMI, or coaxial audio connections (from your EVGA motherboard or graphics card) can only pass uncompressed stereo sound.

However, these connections can also be encoded by Dolby Digital/DTS 5.1 Surround compression to a receiver that can decode these signals, and split them up into 5 channels. But this will only work with certain media.

• DVD or Blu-ray movies with a Dolby Digital/DTS 5.1 sountrack enabled can utilize all 5 channels, because the audio in the movie is made to offer invidiual tracks of sound to each channel. These individual tracks are compressed to run on the stereo connection, then the receiver decodes this signal to split it up again.
• 3D games and other multimedia however, cannot digitally offer individual tracks for each channel, so your reciever can only decode up to stereo sound.  This is the same even if your game supports Dolby Digital/DTS, which only means they have certified the mix.

In order to get true surround sound from your 3D games or other media, you need to use the analog audio connections from your motherboard.  You can connect a surround speaker system into these connections, or connect them up to your receiver, if possible.