Asus P5K audio problem

[Mountain Hiker]

Using "Front Speakers (L/R)" jack on motherboard (green colored jack):

The audio works fine connecting to computer speakers; however, when I connect it to any of the audio in jacks on my home stereo receiver (Sony STR-DE845) or television (Toshiba) I get a humming noise. Once I play a song on the computer, the humming continues along with the music.

I am using a RCA Audio/Video Combination Interconnect Cable
~On the computer end-a 3.5mm Stereo Male To 2 RCA Female Y-Cable connected to the the green jack. [Video (yellow plug not connected to anything.]
~On the receiver end-the left and right jacks (red and white) directly connected to the audo in jacks. [Video (yellow plug not connected to anything.]

I have done the following:
~removed the cable from the computer and connected to other sources (IPOD & TREO)-WORKS FINE
~removed the cable from the computer and hooked up the TV to the receiver-WORKS FINE
~removed the cable from the computer and connected to another computer [Dell Inspiron (Laptop)]-WORKS FINE
So I know it's not the cable.
~don't have another receiver, so I can't test the computer with another receiver.
~contacted ASUS & SONY-not much help
~connected to the other audio jacks on the motherboard including the audio jack on my case-SAME PROBLEM

Is it possible that this particular motherboard has compatibality issues with this particular receiver? I've never heard of a motherboard having compatibility issues with a receiver.

I don't have a spearate audio card and I am trying to make this working without having to buy one.

Thanks for any help you can provide.

 

[Zap]

Do you have the front case ports connected? If so, try testing it without those connected.

 

[Mountain Hiker]

Great idea; I never thought of that. However, after disconnecting all of the front case wires, including the power wires, there isn't any change to the humming.

 

[VirtualLarry]

ground loop hum. Are both the PC and reciever connected to the same power outlet circuit? Do they both use grounded plugs?

I think you can buy an audio isolation transformer at radio shack to alleviate the problem.

 

[Mountain Hiker]

Not sure if they're on the same circuit but they do both use grounded plugs. However, the laptop, which works fine with the receiver, is pluged into the same outlet as the desktop. So, I would think that if there was a problem with the house wiring it would affect the laptop as well. What do you think?