External HDDs getting hot.

Recently I re arranged my external HDDs. and for some reason they show up on Hard Disc Sentinal as running around 52c.
I can explain what all the HDDs are for , but currently I have 7 external and 5 internal, 4 USB hubs.

To narrow problem down I will mention the problem I have without going into detail the extent on the HDDs.
If you want to ask that is fine.

2 Seagate external drives with the 2 usb on front of each.
One goes to 2 WD storage drives.
Other one goes to a small usb WD drive and a notebook style external HDD.

Both Seagate drives get plugged into the motherboard.

All WD and Seagate drives hooked to the USB are getting hot. Exception is the small pocket drives.

Anyone have an idea on why these are getting hot (luke warm to touch) or what I can do about it. Am I better just leaving it.

Hi i think the temps are a little high but not that bad. ideal operating temps should be between 35 and 45c

I dont understand while a drive that is not in use should be running this high, it did not run this high until I redid the connections

I would make sure there's no activity by monitoring processes.

Could be indexing, real-time antimalware software scanning the drives, anything that would increase disk usage in the background.

Is it possible the pc power supply voltage is dropping?

nothing is indexing as far as I can tell. Except maybe a backup program, will have to trouble shoot that .
As far as HDD sleep settings, there is no way to set individual drives to sleep as far as I am aware.

I did this and they are still running hot.