I have a bunch of internal, 3.5" HDDs which I connect them to my laptop using an adaptor which converts SATA/IDE to USB 2.0. I can choose the "Safely remove storage" option in Windows 10 and it removes the access to the drives, but the HDD itself still is powered on and if I cut the power to it, a bad noise of sudden power outage to the HDD can be heard.
I use an ATX PSU for powering up the HDDs and disconnecting the USB adaptor from the laptop doesn't power the HDD down, so the solution to this similar question doesn't apply here.
I'm wondering how are HDDs in PC are powered off without suddenly cutting the power when you shut the Windows down?