My D: drive is only used for backups (mostly) and I want to have it spin down when it has been idle for a while. If I use Power Options that would sort of work as the system disk isn't idle for long, except when the PC is unattended. But that causes one of my external drives to vanish, so it's not a good option. Besides, I don't want the OS to spin down the system disk unless going on standby.
Back to focus: make D: spin down after 20 minutes idle, leave other disk power settings unchanged. I think there is a registry tweak but I can't find the article about it.
The PC is on 8.1 update 1. The internal HDDs are C, D, & E
In my tower I have 2 Extra drives mounted in slide out caddies that can be turned off with a key. I originally bought them from Maplin in Aluminium, but this seems to be a later version. I also have a spare one that I keep elsewhere and to which I make occasional clones of the main drive.
@Fruit Bat /\0/\ "It should already do as you stated"
It's a bit complicated. When one of my external drives started dropping out of Windows ken I set Power Options to power off disks after a looong time. The external drive stays visible to Windows now, but the D drive stays spinning. I don't want an attempt at a solution for the external drive problem, though. I want D: to spin down automatically after an idle time I set while leaving other disks power settings unchanged.