Do I need jumpers?

I have a couple of wd5000AADS sata caviar green 500gb drives that I wish to use in an external usb twin bay hdd enclosure but they are not appearing ie mounted as drive letters on my pc, even though the pc knows they are there. The 300gb drives they are replacing plug and played fine. Do I need to jump pins 3 and 4 (power up in standby) in order to mount them? Apologies if this is a stupid question!

Hi, external enclosures are not supported, I recommend you to check the link below and then verify the supported hard drives on the enclosure manual.

How to physically install, set jumper settings, and set up a Serial ATA, EIDE, or SSD drive in Windows 7, Vista, XP, and 2000 

Perhaps the enclosure is limited to 1.5Gbps. Try installing the drive’s OPT1 jumper to limit the SATA link rate.

My local pc shop formatted them for me but only one worked. I tried to format the other with win7 and the HP utility but no good. Is there software you would reccomend for jobs like this?