I have a Bio-Star 550se motherboard that is having a wierd problem. The built in sound card has a very high pitch whine to it, even when the power is off to the computer. The computer could be completely unpluged from the wall and I still get a whine in my speakers. I have also used a m-audio transport or transit which uses usb for both the audio and power and it also has a whine, even when the power is off. I'm using a generic steel case and I have the motherboard properly attached to the case. My speakers only have a whine with the computer, I have tried them with other sources (ipod, cd player) and they don't have a whine. What could be the cause of this whine and how do I fix it other than using an external sound card with its own power supply.
If the whine exists when there is not power going to the computer then the computer is not causing the whine. There could be a problem with the cable, EMI from the monitor or other source close to the computer, or something else entirely. But you have proved that the computer has nothing to do with the whine by unplugging it from the wall and there still being a whine.
yup, if the computer is unplugged, then it's not the computer. it's the speakers or something close to the speakers or wiring. try moving the whole computer into another room and see if it's still there
I had a set of Cambridge Soundworks speakers that would pick up a Cuban/Miami radio station with no power whatsoever going to them. It was weird as hell. Also, my old cell phone (a GSM phone) would cause the speakers to make unusual sounds just a second or two before a call would come in. As best I could tell all those speaker wires were acting as one giant antenna.
The wierd thing is, when the audio cable from the sound card is disconnected, the speakers do not have the whine. I don't think it would be EMI because I have tried different cables. And if you touch the wire going to the speakers you get the common buzz that you should get. Should I put rubber washers in between the motherboard and the screws that hold it to the case?
I would bet that plugging the speakers into the sound card creates a grounding/shorting issue that results in EMI. I would try another set of speakers to test that. If the new speakers work fine with the computer, then there is an issue with your old speakers. If the new speakers make the same noise as the old ones, then the problem is your motherboard.
Either way, an issue like this is potentially damaging to your motherboard or speakers. It could be a source of static electricity.
Sounds like some kind of harmonic backfeed. Try moving the power supply for your speakers to a different AC circuit. If you are getting ground loop backfeed it is more than likely caused by somthing plugged into your computer like a network cable coming from a phone line or cable line. There are ground filters to isolate this and also harmonic balancers, a company called DCI specialty makes an adjustable line filter and this will clear almost all gound loop backfeed distortion.