WD15EADS Noise when Idle

I have a WD Green drive (WD15EADS). All is okay when it is accessed. But, when the drive is not accessed (when it is in idle state), there is a continuous sound “TrTrTrTrTrTr…”  that seems to come from the hard drive head: it seems that the drive copies a big files undefinitively… but it’s in idle state… I use this disk as external drive with an enclosure… even when the computer is off (and the drive is switched on) this sound happen…

Anyone had the same behavious… is it safe to keep such disk ???

Thanks

I’d run a complete error check using WinDLG to see if there is a problem with the disk. If it reports any kind of error I would replace the drive.

I have almost the same problem: after upgrading HDD to  WDC WD3200BEKT-22A25T1in my T60 laptop

(Linux/Gentoo 2.6.31.12) it start having starnge constant noise only on battery power, only when almost idle.

hdparm -B 192 makes noise less loud, changing acoustic control has no effects.

Any IDEAS?