Alu Macbook Strange Knocking Sound

[Apple?]

Roughly every 30 seconds the computer makes a split-second mechanized knocking sound (coming from somewhere below the trackpad or keyboard). I've just started to notice it now, but I'm not sure if was making the sound previously. Is this normal?

**update: The sound is definitely coming from the stock hard drive

 

[acfusion29]

hey man i had a similar problem... i taped it and put it on youtube.

Is this what your getting?

http://www.youtube.com/watch?v=ua1X1zhOU1A&feature=channel_page

 

[skorpien]

If it's every 30 seconds, it's just the Mac's power management parking the HDD's heads. Doubt it's the same problem you had acfusion29. Yours was much more frequent than every 30 seconds, and quite loud from that video... The OP says he just noticed it now and wasn't sure if it was there before, leading me to believe that it's a much quieter noise than what you were experiencing. This all falls into the head parking category. I noticed the same thing with my MBP and it nearly drove me nuts until I figured out it was a feature of OS X.