I just tested 4 enclosures and 1 actually allowed me to format however would not work after the wii rebooted. I messed around with that one for awhile and finally decided to test something that I used to have to do on something else.. Boot up your wii and usb hard drive (only tested on externally powered 3.5" enclosures) go to the channel and open it DO NOT HIT START. Power up the drive and after it spins up in about 2-4 seconds hit start. Tested on 4 different enclosures with 100% compatibility! Enjoy!