HDD, formerly boot drive, now a data drive - has become very noisy!

I have a HDD that used to be the boot/OS drive for my Win7 tower pc. I installed a SSD as the boot drive (fresh install of Win7) and moved the HDD from SATA-0 to SATA-1 to use as a data drive.

I moved some of the user folders to the HDD: Downloads, Documents, Music, Pictures and Videos.

Strangely, the HDD is much more noisy than I ever remember it. It sounds like it is constantly being read (or written to). It's a Seagate Barracuda 7200rpm drive and I ran the SeaTools tests (SMART, short self-test, short generic test), and it passes all these tests. It's physical location in the tower wasn't changed, and I never removed it from the tower when adding the SSD.

Any ideas on what might be going on, or how I can better diagnose this?

Here is a tutorial by Brink for using Resource Monitor:
Resource Monitor
Use Option 8 to try and determine what Process(s) and File(s) are using excessive disk activity.

With moving files, it may be indexing (just a guess).

You have a couple of other threads that may be relevant to this issue, for anyone helping with this:
Moving 'My Documents' folder; strange results
Why is my OS installation so large relative to sum of files?

TVeblen said:

When you installed Windows 7 on the SSD, did you disconnect the Seagate drive?

If you did, did you delete the Windows partitions on the Seagate afterward?

Yes to both.

DavidE said:

Here is a tutorial by Brink for using Resource Monitor:
Resource Monitor
Use Option 8 to try and determine what Process(s) and File(s) are using excessive disk activity.

Strange. The HDD is not listed. The HDD has one partition on it, which is Truecrypt encrypted. Disk Mgmt sees the decrypted drive/partition as Disk 1. Resource Monitor doesn't list Disk 1, just Disk 0 (boot drive) and Disk 2 (USB stick). Any ideas on why Disk 1 isn't showing up?

DavidE said:

With moving files, it may be indexing (just a guess).

Could be. That would imply that the HDD would stop being so active once indexing is completed, correct? Got ~220k files on the HDD, so maybe that'll take a while.

colt said:

DavidE said:

With moving files, it may be indexing (just a guess).

Could be. That would imply that the HDD would stop being so active once indexing is completed, correct? Got ~220k files on the HDD, so maybe that'll take a while.

As a followup, I think DavidE was correct. The excessive disk usage stopped after a day or two.