Switch on SATA DVD drive power cable?

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lagagnon
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Switch on SATA DVD drive power cable?

Post by lagagnon » Sun Aug 01, 2010 1:52 pm

I have a Zotac GF-8200 mini-ITX, Athlon II X2-240 system that currently consumes about 32 watts at idle. I can get this down to 28 watts by removing the power cable to my LG DVD optical drive. As I rarely use the optical drive I would like to put a switch on the SATA power cable to that drive somehow.

According to the SATA power cable schematics, there are 3 different voltage lines in that cable (3.3, 5 and 12VDC). However, my understanding is that the 3.3V is not used by DVD drives. I may be wrong. If that is correct I could get away with a DPDT switch on that power cable, otherwise it would be more of a hassle.

Any other ideas on how to do this easily (other than inserting/removing the plug each time ;-)) would be appreciated.

faugusztin
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Post by faugusztin » Sun Aug 01, 2010 1:57 pm

The best solution for your problem is getting a external drive :). But to be serious, any solution you will do will cost more than electricity you save this way.

lagagnon
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Post by lagagnon » Sun Aug 01, 2010 2:09 pm

faugusztin wrote:...But to be serious, any solution you will do will cost more than electricity you save this way.
The machine is intended to be a home server, on 24/7, therefore:

365.25x24x4watts=35064 watt/hours = 35.1 KW/Hx0.09cents per KWH = $3.16 per year in electricity.

As most simple switches can be purchased for , $2 the cost saving would pay for itself in just over 7 months. Let alone other very minor environmental savings.

At any rate, you didn't really answer my question....

bonestonne
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Post by bonestonne » Sun Aug 01, 2010 2:35 pm

Without restarting windows (or whatever OS it has) this will be difficult unless the drive is set up on the motherboard as a device that can be removed. If you can remove the device, yes, you can power it on/off whenever needed to save power.

If you can't "safely eject" the hardware, then it will not be recognized by windows without restarting the computer after turning it on.

But if you wanted to be anal about costs, you also have to factor in the transportation to/from the store. Not even mentioning the time to set it up and put it in.
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faugusztin
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Post by faugusztin » Sun Aug 01, 2010 2:43 pm

lagagnon wrote:At any rate, you didn't really answer my question....
Yes i did - get a external USB DVD drive and get rid of all DVD drives you own. Seriously - how often do you/your family use a DVD drive on all your computers ? Every day ? Ok, you maybe need a DVD drive in that PC. Once a week/month ? Get one external DVD drive for those computers and share it between them (and put it on shelf when not used). I have to think hard for my last use of DVD drive for something else than installing OS :wink: .

JamieG
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Re: Switch on SATA DVD drive power cable?

Post by JamieG » Sun Aug 01, 2010 3:23 pm

lagagnon wrote:According to the SATA power cable schematics, there are 3 different voltage lines in that cable (3.3, 5 and 12VDC). However, my understanding is that the 3.3V is not used by DVD drives. I may be wrong. If that is correct I could get away with a DPDT switch on that power cable, otherwise it would be more of a hassle.

Any other ideas on how to do this easily (other than inserting/removing the plug each time ;-)) would be appreciated.
I did something like this for a secondary SATA HDD before I put in in an external USB enclosure.

Buy a molex to SATA connector and cut the four molex wires in the middle. Buy a switch with 4 poles and a double throw action. (Hope I got the terminology right - my electronics knowledge is pretty shaky. Basically you need a switch with 3 rows of four pins). Wire the molex side of the adapter to the 4 pins that are the 'input' side of the switch (the centre row from memory), and with the four wires leading to the SATA connector to one of the other sides of the switch.

Plug in the switch contraption to a PSU molex power connector and the SATA connector side to your DVD drive. Basically, when the switch is thrown one way, power will flow through the molex adapter and the switch to power the DVD drive connected to the SATA power connector, but when the switch is thrown the other way, there will be no power to the DVD drive.

I share the skepticism of some of the other posters that you could flick the switch to turn on or off your DVD drive while your computer is on. When I was using my version of this switch, I only even used it when my computer was off. I shut it down if I needed to access my HDD and re-booted. I'd recommend you do the same.

Anyway, use at your own risk.

Anyway, hope that made some sense.
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Redzo
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Post by Redzo » Sun Aug 01, 2010 4:53 pm

bonestonne wrote:Without restarting windows (or whatever OS it has) this will be difficult unless the drive is set up on the motherboard as a device that can be removed. If you can remove the device, yes, you can power it on/off whenever needed to save power.

If you can't "safely eject" the hardware, then it will not be recognized by windows without restarting the computer after turning it on.

But if you wanted to be anal about costs, you also have to factor in the transportation to/from the store. Not even mentioning the time to set it up and put it in.
+1
well written :-)
lagagnon wrote:
faugusztin wrote:...But to be serious, any solution you will do will cost more than electricity you save this way.
The machine is intended to be a home server, on 24/7, therefore:

365.25x24x4watts=35064 watt/hours = 35.1 KW/Hx0.09cents per KWH = $3.16 per year in electricity.

As most simple switches can be purchased for , $2 the cost saving would pay for itself in just over 7 months. Let alone other very minor environmental savings.

At any rate, you didn't really answer my question....
I will also confirm that if the device will not "safely eject" you will have to restart PC to gain access to the drive.
But restarting the PC will cause it to use more power so if you are interested in saving money should account for PC pulling lot more power during reboot.

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Post by scdr » Sun Aug 01, 2010 11:17 pm

At least in theory SATA supports hotplugging (e.g., see the Wikipedia entry for Serial ATA).
http://en.wikipedia.org/wiki/Serial_ATA#Hotplug

However doing a search for SATA hotplug it sounds like you need a controller, drive and drivers/operating system that actually support it (e.g. work in AHCI mode, not IDE emulation).
for instance: http://forums.whirlpool.net.au/forum/?a ... 20swap&f=7

Looking at the connector details, it looks like to do it properly one would need to arrange the switch so that certain pins (3, 7 and 13) get power before the rest. (No idea how critical that is.)

(Disclaimer: I haven't tried doing this - just reading the specs it sounds like could be a bother. I don't think I would try it except with sacrificial hardware.)


Other options:

You might be able to find an external enclosure to convert your DVD drive to an external drive. (No sense in having to get a separate drive just for that.) Of course the cost and embeded energy in such a device negates the savings you are after, unless you can pick it up second hand.

Is there some other computer on your network that is likely to be on when you want to use a DVD drive (i.e. put it in another box which isn't on as much).

And of course the basic question is can one work out ways to not have the server on 24/7? (e.g., use wake on LAN, wake on timer, etc.) Which could save a lot more than the 4 watts for the idle DVD.

bonestonne
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Post by bonestonne » Mon Aug 02, 2010 7:06 am

In order to "truly" get your money's worth, you would need to be able to eliminate the watts used completely with whatever solution you're going for.

If you add that switch, sure, you can remove those watts completely, but if you were to move to an external enclosure, the whole enclosure + DVD drive would have to use 4 watts or less (to keep the system as low powered as possible).

In short, less than possible, considering what a power brick would use, and what an external enclosure would use, and what the DVD drive itself would need (guessing 4W by existing information).

Yes, SATA supports hotplug, but it has to support ejecting as well, which I've rarely seen. Some JMicron controllers have it on 1 port (I have an MSI board with 5 SATA ports, and 1 JMicron port that support ejecting hardware). In that case, it would work fine, but you need to have the support for it. If you eject hardware enough times in windows without safely removing it, it's possible to corrupt system files. Yes, it sound farfetched, but it can happen.
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scdr
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Post by scdr » Mon Aug 02, 2010 12:10 pm

bonestonne wrote: If you add that switch, sure, you can remove those watts completely, but if you were to move to an external enclosure, the whole enclosure + DVD drive would have to use 4 watts or less (to keep the system as low powered as possible).

In short, less than possible, considering what a power brick would use, and what an external enclosure would use, and what the DVD drive itself would need (guessing 4W by existing information).
Don't quite follow this. Depends on how much time the drive is in use as well as how much power/other resources were involved in the external enclosure.
By lagagnon's calculations, having the drive not be idle saves approx 35.1 KW-H/year. [BTW - it is watt-hours (watts times hours), not watts/hour (which would be watts per hour, or the change in rate of energy use)]

Assume that the external enclosure only uses power when the drive is in use (it has a real switch so it is turned all the way off, or just unplug it.) So if the drive were to use 35 watts when on (not a reasonable number - just makes the figuring easy), you could run it for 1,000 hours in a year and still use the same amount of power.

Using a secondhand enclosure (or a bare USB to SATA adapter) would help reduce the embodied energy and expense, and bring the payback time down.

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Post by Vicotnik » Mon Aug 02, 2010 1:28 pm

SATA to USB-adapter is how I do it. I connect my regular SATA DVD-RW to it the few times I need it. The adapter has other uses so it's good to have one around. The one I have can be used to connect most HDDs (3.5" PATA, 2.5" PATA and SATA) via the USB interface.

Depending on how often the optical drive is used this is a good option. If I were to use the drive often I would get a small USB powered drive I think. Less hassle with cables and stuff.
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