I have a Windows 7 PC, up to date. SSD for OS, SSD for another disk, but three spinning data disks as well. I can hear the spinning disks when they're doing something.

In the past couple of days there has been constant disk activity - not solid, but disk access once a second that never stops. I've done a virus scan, two malware scans, shut down various services, rebooted a couple of times, made sure there were no windows updates, but nothing seems to make a difference. Looking in the task manager performance monitor thingy it looks like chrome is using the disk, but there's no chrome process listed in task manager - I shut it off.

The two things I've changed recently are:
 - Defragmented my 2TB disk (which is 80% full)
 - Set up Astrill using windows VPN services.

Any thoughts/tips/suggestions? The noise is just annoying.