Glad that that did fix it.
Fans can be an obnoxious source of noise if they decide to go. Somewhere in storage here I have a PowerMac G4 with a fairly rare/valuable CPU upgrade(2ghz 7448) and I managed to kill one of the fans on top of the upgrade card with a stray screwdriver while it was running. I knocked a blade off. That was back when I still lived in my townhouse, and about 5 minutes after that happened(I was doing some benchmarking so just kept going while watching the temps) the neighbors knocked on the door to check on me. Fortunately it was a standard size fan and I have a replacement, I just haven't gotten around to installing it yet.
I have other fan/think it's dead stories that I'll spare for now, but if a noise is especially obnoxious or loud I tend to look there rather than at the hard drive.