G Speed Q Sleep mode

Hi. I’ve received a second hand G Speed Q (USB2 model) I bought on eBay. Everything seems fine, apart from it seemingly never to sleep. I’m using a 5,1 Mac Pro and I’ve tried the G Speed Q in El Capitan and Mountain Lion partitions (where most of my productivity software is) and when I put the Mac to sleep the enclosure continues to vibrate away, the drives inside seemingly going at full tilt, and this is not making me happy. Apparently the previous owner used it in El Capitan, but seems a bit vague about the machine.

I haven’t had much luck with G Tech external drives. I had to have a G Drive Mini replaced when that dropped repeatedly - and then finally - off of my desktop, for it to be replaced by another under warrantee which began to exhibit the same early behaviour, (this has been discarded, and any info has been backed up elsewhere).

If need be, I will discard this box and simply use the Hitachi drives elsewhere (I find them very reliable, as do Apple, and my Macs keep going. In effect, I will have still purchased them for a very competitive rate, so no loss, but I would like to know if this may be a driver issue, or maybe I’ve got something wrong about how it’s supposed to idle? I have tried installing whatever there is to download from the G-Tech website, yet Here I Am…

…Else I can see myself getting another make of enclosure to use at least two of the drives as RAID1 backup. I wanted storage. It’s why I bought the machine.

Hope someone can help.