disk with high frequency noise only on FreeBSD

[Jan Henrik Sylvester]

The hard disk of a new computer makes annoying high frequency noises -- 
probably while seeking -- on FreeBSD 7.2-RELEASE.

I booted up a Linux live CD and could not hear anything doing the same 
kind of access. (To test that, I put a ports tree on a FAT partition and 
did 'cat */*/Makefile' from FreeBSD and Linux.)

Using sysutils/ataidle, I changed the AAM  to different values with no 
effect. (The disk does not support APM.)

What is different between FreeBSD and Linux in this regard?

Is the disk probably broken? (I guess I would be out of luck with 
support if I cannot reproduce it on a different OS.)

The disk is a WDC WD1600AAJS-07PSA0 with firmware 05.06H05.

Thanks,
Jan Henrik