Turn Internal HDD On and Off

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jaydub868

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Oct 14, 2007
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I want to install an illuminated rocker switch on the outside of my pc case to enable me to turn off my internal backup hard drive when it’s not in use. The HDD is SATA II and both it and the motherboard support hot swapping, so this shouldn’t be a problem (ACPI will be enabled). But I’m not sure how to wire it. Sata HDD’s use both the 5v and 12v rails, so it appears the switch will need to interrupt both voltages together to get the HDD to be truly off (I believe the 12v spins the disks and the 5v operates circuitry). Therefore, it seems that the typical 12v rocker switch available at PC mod sites would be inadequate.

The molex sata power cable coming from the psu has five cables:
Wire 1 (orange): 3.3v (not used by HDD)
Wire 2 (black): Ground
Wire 3 (red): 5v (used by HDD)
Wire 4 (black): Ground
Wire 5 (yellow): 12v (used by HDD)

What kind of switch would I use?
How would I wire it?
To make it easier, I can probably dispense with the illumination.

And yes, I know I could get an external back up drive or a hot swap tray that would solve my problem, but that’s not what I want to do.

Any advice on how to do this would be greatly appreciated.


 
You can do this, just use the safe remove to eject the drive first.

Most switches can switch 2 wires at once. As you said you just have to interrupt the 12 and 5 volts. There is also a 3.3 in there, but not used.

If you do this i would suggest you mod a molex to sata connector so there is NO 3.3 to worry about.

Go to radio shack or a similar place to get one. If you want illumination you would need a switch that will run the light on 12 volts. Maybe something like this can be found at an auto shop.

Something like this would work

Shows the switch in both positions so you can see what it does. the switch MUST keep both voltages separate.
White is a molex and black is the sata. The internal slider is colored lightly just to show its 2 positions, dont make fun of my paint skills
clipboard01vx7.jpg


I do not know how the sata controller reacts to the drive still being there while powered down. So do some tests just by unplugging it first.
 
You can do this with the following:

1. Digikey Part # CKN2066-ND, DPST Illuminated rocker switch, $6.41.
2. Digikey Part # CF1/41505%RCT-ND, 150 ohm 1/4 W carbon film resistor, $0.03.

You will need to cut 4 of the 5 wires going to the HD SATA power connector. This will leave you with:

5 wires from the power supply:

P12 - Power supply 12V
P5 - Power supply 5V
P33 - Power supply 3.3V
PG1 - Power supply ground 1 (cut this one)
PG2 - Power supply ground 2 (leave this one continuous to the hard drive).

And on the hard drive side:

H12 - Hard drive 12V
H5 - Hard drive 5V
H33 - Hard drive 3.3V
HG1 - Hard drive ground 1 (cut this one)
HG2 - Hard drive ground 2 (leave this one continuous to the power supply)

Your rocker switch has 6 terminals, labeled 1, 1a, 2, 2a, 3, and 4. Your 150 ohm resistor has 2 leads, polarity is not important for the resistor.

Hook up as follows:

1. Solder PG1 and HG1 to terminal 4 of the switch.
2. Solder P12 to terminal 2a.
3. Solder H12 to terminal 2.
4. Solder P5 to terminal 1a.
5. Solder H5 and one side of the 150 ohm resistor to terminal 1.
6. Solder the other side of the resistor to terminal 3.

Since you didn't cut it, the ground 2 wire is still continuous from the power supply to the hard drive SATA power connector.

You cut the 3.3V wire and they are not connected to anything. Insulate them and leave them unconnected.

Switch will now power the hard drive on/off, and will illuminate when on.

Mounting of the switch, soldering techniques, wiring extensions, etc. are left as an exercise for the reader. 😀

I take no responsibility for case damage, power supply wiring harness damage, etc. Also, of course, if you substitute the switch with a different one, it's your responsibility to pull up the data sheet and get the connection/terminal information from the new switch, since it won't match this one and will change all the connections.

Also, of course, I put this together just looking at the data sheets and doing a couple quick calculations for the LED illumination. I haven't built this or tested it, I could have made one or more errors, so you need to double check it for yourself to be sure it will work.
 
Thanks much to Nukemaster and SomeJoe7777. I really do appreciate the thought you gave to this.

A couple of questions for SomeJoe7777.
- Why the resisitor? Won't that bring the 5v to the HDD out of spec?
- Why attach one of the grounds to the switch?
- Positionally on the molex, which ground is PG1 and which is PG2, or does it matter? Same with HG1 and HG2.
 
Im going to take a guess here. The ground and the resistor are for lighting the switch and the resistor is because of the switch being 2.1v.
 
Why don't you just use the Windows Control Panel? Select Power options, make it turn off any hard disk after 20 minutes of sitting idle. That's what I do and it works very nicely.
 

It is a backup hard drive. Physical disconnection is advisable with those as otherwise a RAID1 would do fine.
 


+1

I do that also, even with my "Vista OS" HDD, and since I have 4 GB of ram, the thing rarely spins up, only when I start games and large applications, most of the time It accesses the 8GB readyboost flash drive, or simply the Ram itself.
 
I think he wants to make it so that Windows does not see the drive in explorer or in disk manager. There would be no way for it to spin up under circumstances. It would be as if it were not connected to the machine at all.
 



1. Resistor is to limit current to the LED illumination to the switch. It is not in the electrical path to the HD.
2. Ground is for the LED illumination.
3. You can use either ground wire as the "1" wire, they are both the same electrical potential (ground). The "2" wire will not get cut -- it will remain continuous from the power supply to the HD.

You may want to pick up one of these SATA power extenders so that you don't have to cut wires that are on your power supply. This way if you mess something up you can just buy another SATA power extender.

This diagram shows how the parts look:

HDPower.png


This shows the connections:

HDPower2.png

 
as a few people have shown, doing this is possible, but im not sure i understand the need for this? it seems unnecessarily complicated. you could just have it always spinning (it wont use that much power). or you could be an eSATA enclosure and put the drive in there.
 


Sorry man, didn't mean to step on anyone's toes.

I was going to just leave it at my text explanation, but he asked some follow-up questions, and when I re-read my own post it didn't seem clear enough, so I thought I'd do a quick & dirty diagram, but before I knew it I had labeled & colored it. :)

Again, didn't mean to suggest that your original post or solution was not good or anything. Hope you understand.
 
You guys really went out of your way. I appreciate it very much. Very, very clear.

So, I assume that the sata connector I choose to dedicate to this purpose would have to be the last one on that branch of the wiring harness (i.e., farthest away from the psu) if I still want to use the other connectors. Otherwise, I would be shutting off power to any connector that comes after it, correct? Or, do I have to dedicate the entire 3-connector branch to that one device?

BTW, the reason I want to do this is to make my backup drive immune from virusus, trojans, etc. and minimize unnessary wear on the drive. I could use an external, but I like keeping the computer as self-contained as possible. I could use a swap tray, but I would be constantly be inserting and removing, inserting and removing. I could spin down the drive, but they have a nasty habit of spinning back up. This contraption satifies all my requirements at the push of a button. Sweet.
 
Guys,

This is a great effort, but a bit overkill. Only a single pole single throw (SPST) switch is required to interrupt +12. If the drive can't spin up, it can't send a ready signal to BIOS, and hence can't be accessed. I've performed this mod many times using the 4 pin molex extention you've recommended, and an old style AT key switch, which makes a very clean looking installation. Similar key switches have been used for many years on hot swappable drive trays.

Comp :sol:
 
Well, you're probably right, the platters won't be able to spin up. But a half connected hard drive doesn't sound all that attractive to me. Given the nominal amount of extra work, I like the DPST idea better.
 


If you use/cut wires on your power supply harness, then yes, you need to do this on the last connector on a chain.

However, if you use the SATA power extender that I showed above, you can then use any SATA connector on the power supply.

Another option would be the internal removable caddy, such as this one:

http://www.startech.com/item/DRW110SATBK-Black-Serial-ATA-Drive-Drawer-with-Shock-Absorbers-Value-Series.aspx

We use these here at work to move drives between video editing machines. They work very well. The keylock on the right side of the dock not only locks the caddy into the dock, but it also supplies power to the drive. Turn the keylock off, and the drive will be powered off and spin down, and you don't actually have to remove the caddy from the dock. There is no way it can spin back up either, as the keylock is a physical switch just like you were thinking of installing.

I drew my diagram using Photoshop - nothing special.



You're correct, interrupting +12V would perform the same function as far as the computer is concerned -- it wouldn't see the drive. The thing that I don't know is what happens to the drive when 5V is supplied and the electronics are running, but the drive won't spin up? In some drives, that may cause it to log some SMART errors in NVRAM, or something else like that. Personally, I would prefer the drive to be completely powered down.
 
Really great post, exactly what I am looking for.
One question, is there a way to add a switch while still using the orange 3.3v wire?
By leaving that wire unconnected you disable SMART features correct?
Not a huge deal, but I am curious if there is a way to connect all wires to a switch.
Thanks for your help.
 
Smart will still function without the 3.3 volt wire. All my SATA drives are 3.3 wireless.

Since my drives are setup a bit different, i have then backwards and used an old molex cable to make custom sata power cables. no 3.3 on molex, no problems after years.
hddp.jpg
 
Whether you use IDE or SATA, just put a switch on the yellow wire...thats the 12v. Thats all thats needed. Anyone who has ever used the Vantec EZ Swap (puts your HD in a front panel tray like a sliding drawer) knows thats how Vantec stops the HD. One point is everytime you change the booting sequence from HD1 or HD2 or both HDs, you'll have to save the new config in BIOS in order to boot. Personally, I've had all my HDs on a switch since the Windows 98 days and never had a problem.
 
Great thread! Anyone have any pics of the finished wiring with the switch? Anyone go to the effort of cutting a hole in the front of the case to mount the switch? Also, I'd like to see the diagrams posted by SomeJoe7777 at pages.sbcglobal.net/wilsondr/HDPower.png, but they are no longer there. 🙁

I want to do this with an LTO tape drive, and the newer ones aren't available in a 3.5" form factor for a slide-out tray in a 5.25" bay. I don't think there are hot swap trays that hold 5.25" devices in a 5.25" bay -- only rack mount. Let me know if I'm mistaken.
 
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