Sound card problem

[RacerZ]

Hi, my sound card is onboard nIVIDA MCP2-S. Yesterday I bought a 5.1 audio system, but after I pluged all the cables and made the tests, there was no sound in the rear speakers. The other problem is that during the test (nV Mixer) the speakers are replaced, the display shows that the rear right speaker is tested, but I hear sound from the centre speaker etc. I tried two driver versions 4.20 & 5.10, no result. 10x