Enegy Consumption: Correctly Scaled Power Supply

22 06 2010

One of my main goals of the NAS project was to make it as low power as possible while still functioning.  For me that meant a system that was largely in standby mode and that when running consumed as little power as possible. My first step was the use of low power hardware (motherboard, disk drive, etc) and then my latest step just this week was to move it to a case with a much more efficient power supply.  In this brief post I want to focus on the power supply overhead I saw in my project.

I had an opportunity to look at the impact on badly matched power supplys in my stepwise process of building my home server.  I first built it in a standard ATX case with a standard ATX power supply (350 W I think?) but I used low power Atom board and hard drives (1 2.5″ PATA and 1 3.5″ Green Series WD)  running Windows Home Server 1.0.  After using it in that configuration I moved it into a Chenbro ES34069 with a 120 W power supply that was more efficient at lower loads.  I took advantage of that opportunity and took some notes about energy consumption.  The following are the measurements in 4 different power states, the energy consumption of the 2 configurations, and the percent change between the two:

ATX Chenbro % Change
Off 3 W 2.5 W -16.5%
Standby 3 W 2.5 W -16.5%
Running – Load 42 W 32 W -23.8%
Running – Idle 39.5 W 28 W -29.1%

In all states the power consumption decreased.  In the off and standby states the drop is really negligible but in the load and idle states the reduction is fairly impressive considering the only thing that changed was the efficiency of the power supply in the setup.  After looking at the numbers I wondered how they compared to if I was to run a desktop in the similar setup.  So I measured the usage of my 1 year old Dell Vostro 220 system to throw into the mix.  I did the same measurements but unlike the other two setups the consumption was highly variable.  To account for that I decided to use the consumption specifications that dell provides because they were right in the range I was measuring.  Here is the beautiful graph I made…

Graphical Representation of Measured Energy Consumption

Graphical Representation of Measured Energy Consumption

Eventually I’d like to take this data and expand it to energy usage in 1 year but for now here are the immediate measurements and comparisons.


Case Migration – Chenbro ES34069

21 06 2010

The day was finally here! I decided that due to reworking my living space it was worth it to officially buy the Chenbro ES34169 case.

Chenbro ES34069 Dreamy Case

Chenbro ES34069 Dreamy Case

That’s a lovely stock photo and perhaps I’ll get a photo of my build up there, but the key to that photo is that it is 5″x10″x10″. TINY for 4 full hot swappable drives and 1 2.5″ PATA space.  I had already speced out my parts I was using in a hope to one day upgrade to the Chenbro case I sought after so I was theoretically ready to go to just move my parts.

And it worked! On the first boot of the new case install everything came up and worked correctly. It was awesome! Many sites by this point have gone over the Chenbro case but here are a few starter things for folks who might have just stumbled across this:

1) The case is tight! To pack everything in there isn’t a lot of space for cables. For example my IDE cable for the 2.5″ PATA OS drive pretty much takes up an entire corner to wrap it around and into.

2) The case isn’t difficult to get apart but it isn’t intuitive either: read the directions.  Getting the bezel off is the hardest part and I found once I could hing it 15 degrees (as the pdf directions tell me to do) I could actually get to the tabs from the front side of the bezel with a small flat head screw driver and push them down to release.  I got one undone by the published directions (I had to google for them under “Chenbro ES34069 manual”) and then the second one I could get to release by the screwdriver method.  I’m not sure if you can do both with the screwdriver from the start but I don’t see why not.  Give it a shot.

3) Sadly the case has more fancy lights than my motherboard has headers. This isn’t a big deal but I get the standard 2 lights on the front: Power and HDD Activity. No separate lights for each NIC or a fault light.  It’s really okay as I’m sharing a bedroom with it :)

Over the next few days I’m going to try to put together a case study for the energy savings of my setup.

WHS: WOL from S3 Fixed

21 01 2010

Finally got the WHS to wake on LAN from S3 again today after I reinstalled the OS a bit back. I knew for sure it was an OS setting when it WOL from an off state accidentally.

Turns out you have to turn off the “allow this device to turn off to save power” check box in the network card adapter settings. DONE!

Low Power Nas New Direction: Windows Home Server

13 09 2009

The plan is to use Windows Home Server at this point. It goes against the idea of every component being as low powered as possible but right now I need/want a middle ground on this project. But like many things coming out right now the best way to save power is to turn things off when you don’t need them.  So my goal has shifted to include this as the main power saving method. Actually, that has always been a large part of the plans but for my sanity I need to suck up about 5 W.

The cons of Windows Home Server are mostly power and cost related.  The cost is about $100 for a retail copy of the product.  Power wise though spinning down disks sounds like it isn’t going to be possible.  This is where the Green Drives I’m buying are a huge boon.

The original plan was to use FreeNAS on a Solid State 512 Memory module.  I believe this model used about 0.25 W of electricity or maybe less or a bit more I’m not sure I don’t have it in front of me.  So the real differences in the WHS setup is that I can’t spin down the storage disks and the the install partition needs to be 80 GB at least…which means a HD. I can’t justify $300 for a SSD large enough for that.

So where does that leave me?  I have two options:

1) Install the the OS on the 500 GB Green drive – The down side to this is that then there is NO hope that I can spin down the storage disks at all.  And this is assuming that WHS doesn’t spin them down already past idle and into standy…but I can’t imagine it does.

2) Install it on an OS specific HD – This is my choice.  In the short run it will take a bit more power but if I can successfully spin down data disks or reduce read/writes to them it could be a savings.

To keep with my “one day we will make it into the Chenbro case” I ordered a PATA 2.5″ disk that is 160 GB.  That should be plenty for the OS, add a second level of HD redundancy with only data drive and most importantly leave open the whole 4 SATA ports for data drives in the Chenbro case. The HD according to specs uses 2.1 W at Read/Write, 0.6 W at idle, and 0.25 at standy.

Model Read/Write Idle Standby
Samsung Spinpoint M HM160HC 2.1 W 0.6 W 0.25 W
WD Caviar Green 500 GB WD5000AACS 5.4 W 2.5 W 0.46 W
Estimate of Flash IDE Module 0.5 W 0.5 W 0.5 W

So what about this energy thing? Lets look at some numbers.


Its been a few months since I started this post and actually have had the Windows Home Server up and running since mid-June I think on the downloadable demo copy.  In the next month I am going to have to buy the full copy and migrate soon.  Since I’ve been running on it I have some reviews of it but for right now lets stick with the power conversation.

There are two ways to save power: 1) reduce the amount that each device draws and 2) reduce the time that draws it.  With Windows Home Server the easiest thing for me to focus on is #2: making sure it is one when I am using it and off when I am not.  I don’t use the server as a 14/7 on box instead opting to use WOL and timed sleep modes to turn it off and on when needed.

In the 3 months I’ve had it online it has used a total of :17.81 kWh.  That’s about the same as leaving a 100 W light bulb on all day and night for a single week.   And the amount used by a CFL in a month.  So basically that comes down to being less than the 200 W the light bulbs in my room use that I only use at night  Iwould guess.  I don’t have that exact measurements but it seems it would be accurate.  Since I live in an apartment and we use electricity for heat and hot water I’d be curious how much of the energy we use is my server. 

So I’d say it is a success. I think WHS does throttle down the drives when they are not in use which is helpful.  The other part of that story is that is 17.81 with an in efficient power supply.  If I put it onto a mini-ITX powersupply I bet it would drop more because the load is always around 38W and peaks at 41W when ALL drives are spinning.  I suspect there is some power loss in conversation that I could cut out.

Hardware Ordered!

24 05 2009

Its been awhile since I wrote about the Low Power NAS Project but here we are.  I’ve ordered the hardware I need to get started:

1) – MSI Industrial IM-945GC Intel Atom Mini-ITX Mainboard – $165

2) Samsung Notebook 2.5″ IDE Hard Drive – 160GB, 5400rpm – $59

Shipping for both was about $10.

Parts arrive on May 28th.

Motherboard – IN STOCK!

24 04 2009

The MSI Industrial IM-945GC Intel Atom Mini-ITX Mainboard is in stock at Logic Supply now for $167 dollars. 

Excellent! Now I just need to review my finances and see if I can/should swing it.

Hardware Update

29 03 2009

The short version is: Hardware Redux!  I’m starting over completely due to a motherboard failure.  My Via En15000G shorted out or something one day when I was working on it and the video didn’t come back up and I got some lovely beep codes.

After a rediciloious amount of testing in so many configurations I’ve claimed the motherboard retired. Dead. Toast. Unpredictable. So I moved on.  As one example of one unexplainable strangeness the mother would post and try to boot with a new stick of RAM only. Perfect. Plug in the power of a cd-rom (not even the ide cable) and it wouldn’t post again, same beep codes, until I put in a pci video card.  And more!

After fighting it for so many months that motherboard is no longer an option. So the question is what is?  My goals/needs have changed a bit since I started this project.  Originally I was going for strictly a file store on as low as power as possible.  Now, I’m looking for something more out of the box and perhaps not just file storage and not as low power as possible.  The projct has drained me from being fun and now I am mostly going for functionality. Sad but true.

I also realized/knew that the best powersaving is to turn things off when you aren’t using them so that will be my focus moving forward just as it was before.  So what is my new “plan:”


Goal: Is still to move into the Chenbro case so to keep all my parts transferrable into it.

1) Case – Standard ATX. Plenty of room for drives, mini-itx board mounts in the holes already, and I have it. Perfect.

2) Power Supply – ATX power supply with the case. Only 10 W of overhead vs the Mini-ITX case.  That is close enough for now even though it is like a 33% increase when the whole thing uses so little.  Hopefully, in the future I can move into the Chenbro and get a more efficient powersupply. If not I saw an ATX like power supply that is more efficient and designed for mini-itx applications.

3) Hard Drives – Data drives will still be WD Green Power Drives.  OS Drive will either be a PATA 2.5″ drive or a 512 MB Flash Module depending on the OS I choose.

4) 1 GB of RAM

5) Motherboard – Here is where all the drama revolves around.  When my goal was as low power box as possible I wanted a motherboard that had 4 SATA and a NIC Card that was compatible with the OS I wanted to use.  The SN18000G Via board fit the bill but was $284 dollars. More than I wanted to swallow today for a NAS motherboard.  So after lots of research I found a few things out:

A) Intel Atom chips are about the same energy usage on barebones system.
B) Most new mini-itx boards use the Intel 8111C NIC Chipset which is not compatible with FreeNAS right now. 
C) 80 GB 2.5″ PATA and SATA drives are about $45 each (needed for the one of the two OS choices outside of FreeNAS)

If I give up the ability to use FreeNAS out of the box I found the MSI Industrial IM-945GC coming out April 11ish.  Sporting:

– 2 GB NICS (Intel 8111C of course)
– 4 onboard SATA
– Low Atom Processor
– 1 IDE channel
– No multimedia output options past sound

Perfect! Also, by not being out yet it gives me some time to HAVE to walk away from the project. Not to much of a problem.  Oh and it sports all that for around $167+$10 shipping. 

So the next decision is OS.  I have two main choices right now:

1) ClarkConnect
Pros : Linux Based / FOSS – Free, Can use existing 20 GB laptop drive I have, no more costs besides motherboard NEEDED for system
Cons: Linux Based – my printer is not supported for a network shared printer via it, never used it before, don’t know many people who do

2) Windows Home Server

I know right? My coworker uses this one and is impressed by it. While the idea of being a windows shop at home is one way NOT what I want the other part of me knows I work with Windows all day at work, and coming home to system where I already know how to support it would be nice.  I love learning but I don’t want to HAVE to learn to suport a critical piece of my system at home. 

Pros: Same as work life, lots of cool plugins for things like media, backups, powersaving, easy to connect from other places besides my house, its way of managing HD’s is interesting but allows me to selective make sure all my data is on two hard drives in my apartment whether both those HD’s are in my NAS or one is in a computer and one HD in the NAS
Cons: Costs – $100 for software and $45 for an 80 GB HD WHS needs, monocolutre of MS with MS at work and home

So the decision hasn’t been made because I’m waiting for the motherboard to become available. Once I can get my hands on that I will see what the other pieces dictate as far as OS goes.

Till then!