Great thread guys! I just registered to say thanks - you have saved my sanity and my silent PC!
I just bought a WD Scorpio Blue 500Gb 2.5" drive to run in my silent HTPC. The drive is perfect, almost totally silent, with your ear right up to the drive itself you can only hear a faint fan-like noise when transferring data. Move a couple of feet away and it's so silent it could almost be a SSD.
...at least that was what I thought while I set it up, installed Windows 7 and loaded my iTunes collection onto the drive...
When I came to use the PC 'for real', I started noticing a loud clicking noise every 5-6 seconds, coming from the drive.
I'll skip the hours of searching the net I carried out to try to find the reason for this noise, followed by fruitless attempts to get a response form WD support (email reply within 24hours? not a chance...so far been 8 days and nothing!). Also, note I hadn't spotted the Load_Cycle_Count (which was up at 1250 for only 19 hours use

) until I found this thread - it's the noise that bothered me, but seeing that count would have made me return the drive if I hadn't found a solution.
Anyway I found this thread and tried the WDIDLE3.exe utility, both versions v1.00 and v1.03. Ran them off a USB DOS boot disk. I needed to disable AHCI in the bios to get them to work, otherwise they just popped up with drive not found error (v1.00) or hung the system (v1.03). With AHCI off, booting DOS and running the PC in IDE mode, the WDIDLE3.exe loaded and reported the drive as follows:
WDIDLE3 Version 1.00
Copyright (C) 2005-2008 Western Digital Corp.
Configure Idle3.
Model: WDC WD5000BEVT-22A0RT0
Serial: WD-xxxxxxxxxxxx
Idle3 Timer is enabled and set to 4000 milliseconds.
Wtf? The APM is set at 4 seconds on this drive! That's insane!!!
No wonder it's ticking like a clock!
I then tried to disable using "WDILDE3 /D". With v1.00, this seemed to work and both v1.00 and v1.03 report timer disabled. ...however when I reboot and load up Windows 7, there was absolutely no difference, it was still happily clicking away every few seconds. Using the same command with v1.03 does not report timer disabled - instead it says the timer is still set to some very high number... but again no effect in Windows 7. Setting the timer to various other values also had no effect.
So I turned to hdpram. As with WDIDLE3, I found hdpram only runs with AHCI disabled in BIOS, but it's a small sacrifice for silence. Then a simple:
hdpram -B 255 hda
...stops the clicking!!!
I then followed the excellent write-up by
swivelguy2 on page 7.
Only needed to make a couple of changes to that method because I don't use a log-in password on my Win7 HTPC (it's a single user machine) and Win 7 complains that you can't set a scheduled task without password. If you're in the same situation, it's an easy fix - just don't tick the "run whether the user is logged in or not", and set the task to run "at login" not at startup.
And that's it, a perfectly silent HTPC is possible with this drive and Windows 7. All this headache to fix a 'feature' that makes a decent drive incompatible with modern operating systems...
Steve