"Clicking" and "popping" noises with usb connection
I'm in week 3 of installing my carputer. Here's my setup:
- PIII 500MHz, 256MB, 200GB, all in a generic, old, steel case
- Vortex 750 watt inverter
- Sony XA-300 hooked up to my Sony HU
The inverter and computer are in my trunk. I run a 10' USB cable from the computer to the XA-300. I thought that by using a USB connection I wouldn't have to worry about line noise, but I was wrong. When listening to music I can hear random "popping" and "crackling" sounds in the background. The weird thing is, the amount of "popping" and "crackling" noises I hear depends on which program I'm using. For example, when using winamp I can barely hear any of the noises, but if I use MediaCar or Road Runner the noise is almost unbearable.
I've searched for XA-300, and I read about a guy who has one, and he had to ground his case to stop the noise. I have a 2' 6 gauge wire going from my case to the ground connection on my inverter, then another 2' cable that goes from the ground on the inverter to a bolt in my trunk. I still hear the noises.
Here's what I'm thinking might be the problem:
1. I need stronger connections between the case/inverter/car body, and/or shorter or lower gauge cables.
2. I'm using the integraded USB ports on an old PIII motherboard, maybe I should get a PCI USB card?
3. The USB cable that connects to the XA-300 runs parallel to the wire that comes from my car battery, is that a bad idea?
4. Maybe I should run the ground cable from my computer directly to the car body?
I'd really appreciate any feedback anyone can offer. At this point I'm ready to use the RCA jacks on my XA-300 with a ground loop isolator if it will get rid of the noise, but then I would give up the digital quality of the USB connection.