Power consumption

I'm in the process of planning what'll basically be a file server to store all my music. I want the box to consume as little power as possible since it could be on 24x7.

The box will be headless and should sit pretty much idle most of the time except when streaming files over my 802.11g WLAN. It won't have a fancy graphics card, sound card or anything like that - just a couple of big HDDs and a minimal OS.

The question is - are PCs quite efficient in that they generally only use what they need to?

For example, does a higher PSU rating alone, e.g. 380W v 250W, mean that more power will be used (if all other components remain the same) or do components only use what they need?

If anyone has any recommendations for low-power CPUs or motherboards then I would appreciate those too! :)

thanks in advance

the power supply only takes what it needs as far as i know. are you using the comp for music encoding, or just downloading? you could always look at the VIA EPIA boards for something like that as they are very low-power.

Encoding will be done another box - so this one is purely for storage and so that my main machine doesn't need to be on all the time.

I'll check out the EPIA boards.. thanks.

Components only consume what they demand. The system you describe, if left unchanged, will consume miniscule amounts of power but you should always plan for highest demand. I would suggest going for a mobile CPU and motherboard and one big HD or a smaller main HD to hold the OS and a USB HD to hold files. You could get away with a 200W PSU and still have headroom. If all you want to do is filestream you don't need a fast CPU or HD. Why not just speed up your main rig and stream from there?

Yes they only take what they need but not all PSUs are equal in terms of efficiency. I don't know how much difference in real world savings on your electric bill but for what it's worth this article graphs the efficiency of a whole load of PSUs under various loadings. You can atleast make an informed decision.

http://www20.tomshardware.com/howto/...supply-38.html

A system based on a pentium-m will consume only 22w compared with 67-115w for regular desktop CPUs.

http://www.anandtech.com/cpuchipsets...spx?i=2342&p=3

You can get a socket adapter to make the pentium-m work in regular desktop motherboards. The additional upfront expense you can offset against savings in electricity but how long it takes to pay back I don't know.

http://www.anandtech.com/cpuchipsets...oc.aspx?i=2382

I've shyed away from using my main PC since it's a fairly high spec P4 system running XP and I was under the impression that it would be better to have a second, low power system dedicated to streaming files (saving on elec).

Additionally, my main PC sits upstairs and the consumer of the music stream (Squeezebox 2) will be downstairs in the livingroom so it would be more convenient to site a file server down there for powering on and off in conjunction with my hi-fi.

I think an article focusing on the total cost of ownership including electricity usage would be quite an interesting read. Taking into account any reduction in heat gains it would be interesting to see the savings in running comfort cooling air conditioning. I think we are seeing the begining of a responsible attitude to computer energy consumption from the manufacturers particularly now that many applications don't require additional processing power.

i read a similar article somewhere a few months ago and it found that a standard high-end pc running 24/7 would add £40 a month to the electricity bill. currently, the organisation behind 'Energy-star' is working on a 2nd revision which will require pc component manufacturers to save energy to a far greater extent than is currently employed. this will also include a higher minimum effeicency level of psus. i may have even read this on Hexus, so appoligies if you're all familiar with that article. furthermore, buying a TFT is far more effiecient than a CRT as it requires less than half the power.

whilst i agree with the idea of using the 'mobile' chipsets, i would think that that avenue would be too expensive for a simple file server. the VIA items i mentioned would be less expensive as well as containing basic integrated graphics and sound. just add RAM and a HDD and your away. check out www.mini-itx.com for more info on these products.

another cheap and low-power alternative, would be to look at somewhere like www.komplett.co.uk as they do quite good bundles of older components at good prices.

Basically, your talking about 8Watts per HD, CPU will be around 82Watts, that of course varies depending on what CPU you go for, add another 60Watts say for the controllers on the motherboard.. basically, a 300Watt PSU will more than serve the purpose of supplying a simple server with juice.

Efficency is what you want in a PSU if you are concerned about power consumption. A 600W PSU with 80% effecency will draw less power than a 150W PSU with 70% effeceny, if the system is only using 100 watts.

No motherboard uses 60 watts, not even ones with integrated video.

I would get a lower end Socket 754 chip and undervolt it. My A64 3000+ will run at stock speed with only 1.15 volts. At that voltage and speed it uses about 30-35 watts at maximum load. If you underclock the CPU you could probably get away with using less than 1 volt at 800Mhz. At that speed and voltage you'd be talking about 10-15 watts going to the CPU at full load and an 800MHz A64 is more than enough for a file server.

For the kind of system you seem to want, get a good active PFC powersupply (zippy, pc power and cooling), a quality mobo that lets you use a wide range of below stock voltages, a cheap video card, a single stick of ram, and a single large harddrive. You could easily build a PC that uses less than 60 watts total most of the time.

AOpen A64 mobos have voltages down to 0.8v and I find them to be stable and good performers.

Or, if you can find a decent older system you could jsut add a new hardrive and better PSU to that and be set.

Some interesting points from everyone - much appreciated.

I'm considering 3 options (in order of preference)

1. SFF barebones - something like a Biostar IDEQ 210V or Shuttle SN41G2 v3 barebones together with a cheap video card and a Semperon/Duron

2. min-ATX system based around new VIA EPIA SP m/b

3. standard ATX system

I'm leaning towards a SFF barebones due to it's compact size. Would I be right in saying that these would be quite energy efficient?

ost SFF power supplies are of good qualkity, but other than that power consumption is really not much different than a comparable desktop.

The VIA cpus are very low power and would be powerful enough for what you need. If the cost is equal to or cheaper than the other options go for it.

I have another suggestion:

Buy an Asus WLAN 2.5" HDD or Buffalo NAS thing (or a bunch of them) Then you can stream over 802.11g. Hell you don't even need a computer to do that stuff.

Asus WL-HDD 54g Wireless Harddisk Adaptor (needs any 2.5" HDD) £42.50 £49.94 from SCAN

Yeah - the only problem is that I need to run a server process (SlimServer - Windows/Linux/Mac) - hence the need for a cutdown OS.

I believe that LinkStations can be made to run it (since they run minimal OS) but to be honest I really want a box that will take minimum 2x3.5" HDDs to allow for future expansion.

Found this case (http://www.xcase.co.uk/acatalog/Comp...x_Desktop.html) that seems like it might be upto the job coupled with a VIA SP m/b and efficient PSU.

I'm wondering if you can compile the server process into a Xscale Linux package. Get a cheap PDA with 802.11b/g and Compact Flash slot, slap in a CF->USBx2 card and stick in 2 3.5" USB HDDs. You can use the PDA when you're out and use it as fileserver at home. Power usage will be lower than VIA mini-itx stuff.

It may cost too much to get started though. (Actually may be the same or less than a SFF.)

SFFs are good, but be warned, they are not as quiet as people expect them to be. if silence is something you want, then the ITX way might be better. if you do want SFF and can budget for it, Aopen do a Pentium M based X-cube that might be worth a look.

i've just picked up this months PC Pro, and it as a nice article about building an ITX based jukebox, similar to what you are looking at, and also discusses low power consumption techniques. certainly worth buying.

I've been screwing around with undervolting/underclocking my CPU.

Right now im running at 0.85v, 800Mhz and the computer is perfectly usable. I'm also passively cooling it. Idel temps are 1C above ambient, load gets into the lower 30s (these are tCASE temps, not on-die, obviously). I think this would be the way to go for silence, though in a closed case a very low speed fan or larger than stock heatsink might be needed.

EDIT: droped voltage to 0.8, the lowest I can go. Very stable at 800MHz. Oddly enough, I can still play all my games just fine. FPS is significantly lower, but everything is very playable.

Cheers for the magazine pointer Lu-tze - I'll try and get hold of a copy.

Interestingly, Tom's Hardware Guide stated that the Mac Mini used only 20W when idle.. which sounds great.. now if it was only half the price and had a 300GB hard drive ;)

Quote:

---

Originally Posted by DsW

Cheers for the magazine pointer Lu-tze - I'll try and get hold of a copy.

Interestingly, Tom's Hardware Guide stated that the Mac Mini used only 20W when idle.. which sounds great.. now if it was only half the price and had a 300GB hard drive ;)

---

Its very quiet and will go into sleeping mode when left untouched. The server for windows/ smb and other server functions are easily switched on with one click. Ive stored my entire music collection on mine, and transferring music through my netgear box works perfectly.....ooh, Ive just realised I am trying to sell u a mac...sorry ;) . Anyway Thats the mini, I couldnt resist myself! If you are tempted, use the apple store for higher eductation, you get a 10% discount.

EDIT: Did I mention, its easy to set it up to run headless, and an external firewire HD can be used also. btw how much music do you have anyway?

I've not done half my CDs yet and I'm at 100GB (flac files). After that it's my vinyl and MD collection.. plus I need to factor in future CD purchases etc.

Quote:

---

Originally Posted by DsW

I've not done half my CDs yet and I'm at 100GB (flac files). After that it's my vinyl and MD collection.. plus I need to factor in future CD purchases etc.

---

PC it is then! haha

In case anyone's interested.. I've opted for the setup below. I reckoned it gives the best balance of flexibility, functionality, value and low power consumption.

Living room PC / SlimServer PC

VIA EPIA SP 13000 £150
Hipermedia Chassis £55
Panasonic Slot Load Notebook DVD writer £48
Samsung Spinpoint HDD 80GB £37
Cat5 crossover cable connected to Squeezebox 2 Wireless £2

NAS

Lacie 500GB Ethernet disk £400


Putting the server PC in the living room has two advantages

1. I can take advantage of the Squeezebox 2's bridging capability to allow wireless connectivity (thus removing the need for a seperate card)
2. I can hook it upto the TV for internet browsing

NAS has several advantages

1. Server PC can be small and quiet
2. easy expansion
3. low power consumption
4. can be accessed from any PC on the network

However.. its' pretty damn expensive and I'll need to buy two of each NAS device if I want to keep backups :mad:

Did look at Mac Mini but that would have added about £200 to the price of my server PC so it was a no-brainer.

Anyway.. thanks for all your help and have a good weekend! :)

You could just get a network hardrive. You don't need a whole computer just to share files.

Quote:

---

Originally Posted by oralpain

For the kind of system you seem to want, get a good active PFC powersupply (zippy, pc power and cooling), a quality mobo that lets you use a wide range of below stock voltages, a cheap video card, a single stick of ram, and a single large harddrive. You could easily build a PC that uses less than 60 watts total most of the time.

---

Active PFC is less efficient than passive (or no) PFC. you're better off without it for minimum consumption (unless you're charged for bad power factor).

Quote:

---

Originally Posted by oralpain

You could just get a network hardrive. You don't need a whole computer just to share files.

---

I'm not just sharing files mate - I need to run the SlimServer app to control my Squeezebox 2.

http://www.slimdevices.com/su_downloads.html

How is active PFC less efficent?

Isn't a higher power factor normally more efficent by definition?

Granted the difference is not large, in most cases, but from what I've seen active PFC PSUs are a bit more efficent and lower EMI can help too.

Active PFC reduce line load. Instead of going 10A then 1A current, it averages out at 5~6A, hence saving cable cost. It does not affect power conversion efficiency at all.

DO NOT GET THE LACIE DISK. I've seen loads of people with failed Lacie due to poor cooling design. They're not meant to run for 7x24, I doubt they can even run 7x8.

Samsung Spinpoint HDD 80GB £37 <--Get a Hitachi 5K80 instead.

Save all your trouble and get an imac mini, you don't need to pay for winxp license that way. Do you really need a DVDROM there (let alone writer)? You could copy from network, and I doubt you would burn a dvd from there.

You could play a DVD over network though so there is no big need for that notebook cdrom.

Quote:

---

Originally Posted by arthurleung

DO NOT GET THE LACIE DISK. I've seen loads of people with failed Lacie due to poor cooling design. They're not meant to run for 7x24, I doubt they can even run 7x8.

Samsung Spinpoint HDD 80GB £37 <--Get a Hitachi 5K80 instead.

Save all your trouble and get an imac mini, you don't need to pay for winxp license that way. Do you really need a DVDROM there (let alone writer)? You could copy from network, and I doubt you would burn a dvd from there.

You could play a DVD over network though so there is no big need for that notebook cdrom.

---

Interesting point about the Lacie disk. Will check it out more.

Why do you recommend a Hitachi instead of the Samsung? Is it as quiet?

I was planning on using either Gentoo or Debian anyway so no XP license needed. No way I'm paying another £200 for a Mac Mini.

The DVD writer is there mainly to install the OS. I couldn't actually find a notebook style DVD-ROM drive when I looked - only writers. If you know of somewhere selling one then a link would be great! The case only takes the notebook style.

Quote:

---

Originally Posted by DsW

Interesting point about the Lacie disk. Will check it out more.

Why do you recommend a Hitachi instead of the Samsung? Is it as quiet?

I was planning on using either Gentoo or Debian anyway so no XP license needed. No way I'm paying another £200 for a Mac Mini.

The DVD writer is there mainly to install the OS. I couldn't actually find a notebook style DVD-ROM drive when I looked - only writers. If you know of somewhere selling one then a link would be great! The case only takes the notebook style.

---

The hitachi is 2.5" (I said 5K80 not 7K80)

Quote:

---

Originally Posted by oralpain

How is active PFC less efficent?

---

No, doing more work in the PSU is less efficient.

Quote:

---

Originally Posted by oralpain

Isn't a higher power factor normally more efficent by definition?

---

No. Power factor has little to do with efficiency.
Power factor is a measure of how resistive vs inductive the load looks. Most AC electrical devices are somwhat inductive, which means they will absorb power during part of the AC cycle then release it during the other part. Power companies don't like this because it means you get a load of power being dumped back on the grid out of phase with the main supply. Power companies thus like your devices to have a power factor close to 1. Active PFC is some circuitry which makes an inductive load (like a transformer) look like a resistive load (like a wire). This is great if you're a large industrial company charged for how good or bad your power factor is. It means nothing to residential customers though as power companies don't charge them for poor power factor.
Active PFC uses power to do it's correction (hence the term active), which means active PFC supplies are less efficient than passive or no PFC (all other things being equal).

Quote:

---

Originally Posted by oralpain

Granted the difference is not large, in most cases, but from what I've seen active PFC PSUs are a bit more efficent and lower EMI can help too.

---

Active PFC supplies are usually more expensively built, which is where the efficiency and lower EMI comes from. The fact that it has active PFC is irrelevant to how efficient it is - it's largely just a gimmick to sell expensive PSUs.

I believe PFC is a requirement in the EU nowadays or is/was going to be.
I know they`ve already mucked up a lot of the older standards and regs.

But read http://www.endpcnoise.com/cgi-bin/e/pfc.html here and make your own mind up with correct info.
Or google for many other links.