New soundcard- loud screeching static noises when plugging in rear/bass jacks

[havingfun1]

I've recently bought a new Asus xonar DSX 7.1 soundcard for my computer, and installation was fine. However as I was pluggin in my speaker wires into the black and orange jacks, a loud screeching noise ( like a nail scratching a blackboard) is produced from the rear and center speakers. This didn't happen on the old soundcard i had which broke.
Is this something with compatibility?Or is the product defective?
cpu- i5 3570k
Mobo - GA-Z77-D3H
gpu - radeon DD6870
Windows 7 64bit

[g8ina]

That sounds like digital audio to me, check your settings make sure the jack isnt assigned to SPDIF or something.

[havingfun1]

I checked in the asus audio centre, and made sure the SPDIF box was unticked, but the problem still occurs. From the subwoofer I have 3 wires: Green- front speakers ; Black - Rear speakers ; Yellow - Subwoofer/center. It's only when the black and yellow wires are plugged it does it make the screeching noise

[Dutchjonsey]

Check and see if the microphone input playback is on, I had a similar noise on my Asus 5.1 card, it was picking up the interference from the front panel audio, which wasn't properly grounded on my case.

[havingfun1]

I don't think it is. I checked anyhow, and it isn't on... I think. My friend came over today, and he brought his soundcard as well ( exact same one). Same problem. We checked out the speakers and decided it's probably the subwoofers problem, with the connections to the jacks. The speakers I'm using are old dell 5.1 speakers, so I might have to buy new speakers?

[watercooled]

It could be some sort of grounding problem. Do the speakers work OK with a laptop running on battery (so not grounded) for instance?