Help with Surround sound system

[Joeh21]

Ive recently turned to pc gaming, and i noticed a big difference in my sound compaired with console
I used to hears 5.1 perfectly, but on pc its the front 3 speakers are load but the rear ones are barely noticable
I tried configuring it but it only allows my choose stereo

I have my pc hooked up to a 32" lg tv via hdmi, my HM system is plugged into the headphone jack on my tv.
The only output on the sound system are hdmi and the red white and yellow ports. I use the white and red to connect to my tv
How can change this to surround?

 

[linkgx1]

Usually the red and white rca cables don't support surround (unless the content you are usually have Pro Logic II...even then). What kind of soundcard does your PC have?

 

[Joeh21]

Just the reltek audio built into the motherboard, but my sounds works through my graphics card. Msi tf3 7950

 

[Joeh21]

Anyone?