How to make external hard disk sleep/stand by in Windows 7

Hi,
I'm using Dell studio 1558 laptop with Windows 7 and 8 in dual boot.
I've 2 external hdd, WD my passport 0740 and Sony HD E1.

well in windows7, these 2 ex-hdd or any one of them doesnt go to stand by,
but in windows8, they go to stand by (stops spinning, indicator led goes off).

In both, windows 7 & 8, same time duration for "turn off hardisk after" are selected, and all other power options are same, I've checked.

Even i face the same issue with my windows 7 in desktop.

What should i do to make them go to stand by in windows 7 ?

I would shorten the Sleep period before it proceeds to Hibernate, to take advantage of the Hibernate function which is perfected in Win7.,

I set my installs to Sleep at 30, Hibernate at 45-60. This writes the desktop to HD and shuts the PC down, whereas Sleep keeps power to the RAM and apparently the USB ports. When you resume from Hibernation it also starts up much faster.

Well thanks for the reply, but i was talking about stand by of external hard disks, not windows'.
and i never set power option to sleep or hibernate my system while in AC power.

May I ask why not? Many say this because of old XPired worries. As I said Sleep and Hibernate are perfected in Win7.

As far as I know an external HD is not meant to sleep until the OS does. Any USB suspend is going to be related to the OS suspend. You should at least try it to see.

well i mentioned earlier, my ext.hdds go to stand by mode while not in use but windows remain active not sleep or hibernate mode ...in windows 8.

I keep on work on files in internal hdd for hours, and put back ups in ext.hdd after completion of work. so during work, why should i put the windows to sleep/hibernate. And i dont repeatedly attach/detach ext.hdds.

Anyway Thanks