This problem is causing me a headache, and I know it's a software problem somewhere.
Windows 7 64
Radeon 7870 - HDMI out to Denon E400 receiver
Just to preface this, my speaker connections are correct as tested via Windows, the build in test of the receiver and verified with other sources ala. PS3 and 360.
Windows is set to 7.1 surround correctly, the built in Windows sound test correctly plays through all speakers. The problem is when I load a PC game like Battlefield or L4D2 I only get 5.1 *but through the back surrounds not the side surrounds as it should. The side surrounds are totally quiet. The game settings are correctly set for surround. In the case of L4D2, it's specifically set for 7.1, but even set as 5.1, I incorrectly get surround sound out of the rears and not sides.
I have wasted a bunch of time on this, but haven't found an answer yet. Hoping someone has some experience with this issue.