There's a stupid low frequency rumble noise that happens approximately once every second. I can only hear it in about 3/4 of my room, covering both my bed and desk, unfortunately.
I'm suspecting two different sources of noise, or something is reflecting the sound waves and causing constructive interference near the center of my room.
Unfortunately, it's not my hard drives, as I first suspected.
It kept me from sleeping for a few hours last night. Doesn't seem to have let up. :\
It's annoying though. Blargh.