I have a 5th gen Airport Extreme, Apple refurbished, that makes buzzing noises on data downloads. The noise sounds similar to a spinning hard drive, but no hard drives are attached to the router, nor are there any in the area of the router. When it sits idle, the buzz noise doesn't sound. I have about 2 weeks left on the one year warranty, should I have Apple look at it, or is that noise always there and I just started noticing it? I haven't seen any negative performance on my network lately.