Drives are not meant to be run in that fashion, no way shape or form.
They need air above and below them, they can not "touch" anything while running. The spindle will build up heat and static electricity.
Mount those things in a chassis or some such thing. Don't just leave them out there like that. They are building up heat underneath and will fry.
http://images.google.com/images?q=ex...ff&sa=N&tab=wi