I don’t know if it’s normal or if there is a batch of Extreme 240GB’s that have this “problem”?
I have 3 x 240GB Extremes.
1.Completely silent apart from VERY quiet noise when writing to the drive.
2.Very noisy all the time, even when not being written to.
3.Just like yours - a little bit of screeching sounds for the first few minutes, then quiet
I bought #1 and #2 as a pair and was concerned about the noise #2 was making, so I returned it as faulty. Unfortunately, the replacement (#3) is better but still not silent like #1 is.