I got this weird sound coming out of my cheap speakers every once in a while. it has nothing to do with computer hardware because there are no such sounds from my headset and the noise continue to appear even when speakers are not connected to computer. We also had speakers on a ceiling at school and i heard the same noise coming from them. I think this is it, but not sure: "If it is a true 60hz tone you likely have what is commonly known as a ground loop. The hum is produced by small currents flowing through the shields of the unbalanced analog cable toward the input of the recording device. The best (and safe) solution is to make sure all your equipment grounds terminate at the same point. Easier said than done. Other sources of hum/buzz are anything that creates strong magnetic fields: CRTs, PSUs, electric motors, certain types of lighting, etc. Always keep low-level cables away from these sources. If you have to cross low-level signal cables, and power cables make sure you cross at right angles. Don't run parallel. More info here.http://www.rane.com/note151.html"