Can you make 2nd HDD go to sleep?

Solution
Also check your power settings in the control panel, there is an option under the advanced settings that allows you to turn off hard Disks after a specific number of minutes, if it's set to Never the disk will never turn off. By default I think it's set to something like 20 minutes which means that after 20 minutes of inactivity the drive will power down.
It depends on what's on it, if you put a web browser cache or on it or something that gets accessed often, it probably won't spin down, if it's just a media drive, it should stop after a few minutes of you not accessing it.
 
Also check your power settings in the control panel, there is an option under the advanced settings that allows you to turn off hard Disks after a specific number of minutes, if it's set to Never the disk will never turn off. By default I think it's set to something like 20 minutes which means that after 20 minutes of inactivity the drive will power down.
 
Solution