Just pulled out the old drive (and DVD player for good measure) and the random disk pinging noise persists.
In the above configuration I also heard the disk pinging noise just once when in the BIOS screen, I started selecting menus and etc to see if it would happen again but it didn't. This implies that either the disk is faulty or I have a virus in the BIOS. I'm betting on the problem being a BIOS virus as I have 2 drives (Seagate ST2000DM001-9YN164 and Seagate ST3200827AS) that exhibit the same problem.
Will Avast detect and clean up BIOS viruses? The BIOS is Award Software International, version F7 (31/3/2006), on a Gigabyte motherboard of the era, 8194PL-G.