tom2u :
That sounds like one useful program. Unfortunately it doesn't work on my present OS: XP 64bit. But I can use it later when I dump this useless OS.
Question: Is there one wire I can disconnect to power down the drive or will I have to have a multiple pole switch to handle 2 or 3 wires?
That's odd, there's a 64 bit version there in the download too and I used to use it on my pc at home when I had XP 64 installed.
They must have changed something in it. Maybe try an older version, 1.1.0.1 or so.
(Very simplified here so don't jump down my throat any of the more propeller-headed guys out there): Effectively the 5V drives the baseboard of a hard drive, the 12V drives the two motors, head and spindle and the 3.3V powers the logic (on-board memory)on most (cheap) sata connectors the 3.3V isn't connected because the 5V line is good enough to run most logic (hence USB flash memory)
It depends on what you want to risk really. if you shut off just the 12V, yes the motors will stop running but the driver circuitry will still keep trying to spin it up and will fail out or in the worst case burn out.
If you stop the 5V... look just don't do that, it's too hard to explain but it's really high probability of screwing up the base board.
As for cutting the ground line... well if the engineers did their job perfectly, there's no problem but if not, adios to your drive.
Just get a mini 2 pole switch and connect the 5V (red) and 12V (yellow) to it that should do the trick well.
Having said all this, when you spin down the drives with Hotswap or disable the drive in Device manager they disappear from windows explorer too.
Alternatively if you just want them to disappear and are not really too worried about the energy used, just remove the drive letter from disk management (diskmgmt.msc)
I can post you a cmd script to do/undo this last thing if you'd like.
P