So I just got 4 new 2TB WD green drives (well they are not new, but I am in the process of testing them). Anyway, I am running HDTune error scan on one of them right now via an external USB 2.0 enclosure. The default error scan is at 21 hours running and has gotten through 1833GB of the hard drive. So I think a full 24 hours and it will be done. My question is this. Is there a big difference between the full error scan and the quick error scan? The scan rate right now is 25 MB/s which I think is mainly due to the USB enclosure, but I don't want to take my computer apart just yet to plug these things in.