FAT32 under windows only works to 32GiB due to software limitations. Filesystem Limitations
you need to reformat the drive as NTFS, possibly zero-wipe to factory condition first in order for the usb external drive case to work it does its own partitioning. I had problems recognizing my 250GB drive in XP using FAT32 - I partitioned and formatted it using part240 I think (now I just use gparted to shuffle/create my partitions most of the time). I tried reformatting the drive as NTFS and sticking it in the drive case, don't rightly remember, but I think this did not work either. I had to zero the disk if I remember right because the chip in the case does its own special thing with partitioning or something. they are probably not all the same either.
your mileage may vary when it comes to usb external cases, but the part about FAT32 will be a constant with Microsoft very likely, because I think they are trying to keep compatibility with older software, including older bugs and limitations... (ugh!)
FAT32 I think can handle 8TB with no software limitations.