A friend of mine used a working scrap Core2 HP workstation that had 2 IDE channels and 6 SATA 2 ports onboard, along with a PCI SATA card to DBAN all the old hard drives getting scrapped at his work years ago, so he could do 4 IDE's at a time and 8 SATA drives. Had it running in a corner of their storage room for a couple days and he'd just check on it and swap drives/print out certificates as he went.
I ended up with 12 40gb thin 5400rpm Seagate drives out of that, + a mess of others.