Usually if the drive itself is bad it will make some really distinct clicking noises when it tries to spin up, but from what you describe and the fact that it is all 7 disks, it sounds like the SATA controller on the motherboard (or something further up the chain) is a more likely culprit.
get an external USB/firewire enclosure ($15-$50 USD) and try connecting the drives that way.
EDIT: oops, see you tried that already. Your best bet would be to look for a circuit board from the same model drive and swapping them.
If they still don't work, maybe the freezer trick, but before you try the freezer trick (worked like 3/4 times for me) you will need to accept that the drive is already gone. Put it in your junk drawer for a day or 2 so you can learn to live without it.