Hard drive harmonic

I noticed that my hard drive starting making a humming that was of a lower pitch than normal. I wasn't totally sure what it was but I decided to shut off my laptop for a while since it had been on and active for about 15 hours. When I turned it back on about 20 minutes later the sound came back. I put in my 12 cell battery, which makes the whole laptop sit higher at the back. After that the sound went back to its normal hum.

I was wondering if its common for hard drives to change pitch like that and what was the cause? I want to say it was unbalanced but HDD's are very sealed so I don't see how something found its way in there and changed the balance.

I hope its not going to fail on me. The one time one did fail it was a slow painful blue screen, crash filled, take-6-months-to-load-"my-computer" train wreck. I have my data backed up too :) so no big worries there.

FYI: My laptop is a HP dv4-1220us and the HDD itself is a fujitsu mhz2250bh g2.

Thanks for the help!

If you're concerned about the state of your hard-disk install speedfan and check the SMART tab. The readings you should look out for are reallocated sector count and bad sector count... if these start to rise your hard-disk is dying.

About the "hum" - it's normal for hard-disks to produce various kinds of low vibrations as they spin their disc at a significant RPM. There's a reason why PC quiet enthusiasts put rubber wafers under them.

Bottom-line: unless the SMART data suggests otherwise I wouldn't really worry about it.

Ahh, it says the drive is happy and healthy. Thanks. Turning on my desktop made me realize that I cant hear its hard drive over the fan