A tale of two Seagate thingies. I have two Seagate GoFlex SATA interface devices which I can use to mount bare 2.5-in HDs. One connects via USB 3.0, the other via Thunderbolt 1.
However, in DiskUtility, any drive connected via T/bolt shows as S.M.A.R.T. verified, whereas the USB 3.0 adaptor shows S.M.A.R.T. as unsupported.
This would suggest something amiss with the USB 3.0 jigger. Somewhere I have a similar adaptor that connects via FireWire 800 but I can't find it at present.