power supply - How to force a hard drive to shut down

I have a hard drive in my computer that I'm not using. I want Windows 7 to shut it down. I don't want to have to manually remove the cable.

(The reason is that for some strange reason my computer will not boot if it's not connected. disk boot failure after upgrading power supply)

I know that Windows 7 will shut it down after a certain period of time of it not being used. How can I force it to shut down without having to wait for this?