5.1 woofer system for computer

[yrana2002]

I have a philips 5.1(5 speakers + woofer ) system which i want to put in my computer. I bought an RCA to jack wire, however that wire is for a 4.1 system.
using it, ive noticed a lot of crackling sound and irritating bass from woofers and speakers.

Is the problem due to the 4.1 wires, or could there be another way to do it? Kindly tell me

[desiibond]

if you can post some pictures of your woofer's rear connectivity and PC's output ports, it will be useful.