I just got the logitech z607 surround sound system for my PC however the system is shipped with 3 RCA cables and my 5.1 built in sound card from my motherboard (G1 Sniper B5 for anyone wondering) only has 3.5 mm inputs but should support 5.1 . WOuld 3 RCA to 3.5 solve it (for full 5.1 not emulated or anything) or are the speakers not right for 5.1 on pc or do i need to buy an external sound card. Thanks for any help!