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Energy Efficient Desktop PC

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April 5, 2012 10:22:50 PM

Hi

I wish to build a energy efficient Desktop system

My current desktop is eating approx 300 watt of power. (including monitor)

My aim is to build a desktop running no more than 50 watt (ex. monitor).

I am planning to use a i5-2557 or so. INTEL states it eats only 17Watt. But any input on CPU is welcome

HDD is most likely to be a WD CAVIAR GREEN, as it only use 6 watt spinning, 0,8 when idle. (Almost half of the Seagate Barracuda). However, Info from competitors is hard to find.

The important factor for a energy efficient system seems to me to be the motherboard, but info of energy use is not easy to find. ASUS, for one, have no help.

Looking around the net, I find only little help how to build a energy efficient system. Hope someone can help
April 5, 2012 10:49:55 PM

Lots of computers use very little power. They are called smart phones :p 

My point being that you have to decide what you want to DO with the computer before you can decide what the minimum power requirement will be.
Related resources
April 5, 2012 11:07:42 PM

1. Wait for Ivy Bridge and use their dual core cpu
2. Use Z68 chipset mobo so you can undervolt the CPU/GPU
3. Use the built in graphics of Ivy Bridge
4. Use only 1 stick of ram
5. Use SSD instead of HD
6. Use a 80+ platinum PSU


April 5, 2012 11:38:47 PM



I built an HTPC last summer that would be more than adequate for most any non-gaming use. In fact, I am getting ready to build a similar desktop PC, although with a more traditional case, and likely micro atx instead of mini, and one of the standard i3s, instead of the 2100t.

Here are the components from the HTPC:
i3 2100t with stock cooler
Intel DH67CF motherboard
4gb ddr3 1333 Mushkin RAM
64gb Crucial M4 SSD
2tb WD greed drive
Asus DVD burner
Apex MI-008 case with included 250w power supply
120mm Scythe fan
80mm Nexus fan

I plugged it into a Kill-a-Watt to measure power draw. At idle (programs open or not), it draws under 30 watts. Playing 1080p content, it gets up to 34-35 watts. It sleeps at under 3 watts.

Note that I am using the cheapo PSU that came with the case. Replacing it with a more efficient PSU wouldn't make any sense. How much time would it take to make up the 3-5 watts I would save (at best)?
April 6, 2012 12:09:54 AM

What is your objective?

The i5-2557 type cpu's are low wattage chips that are intended for laptops.
So far as I know, there are no conventional motherboards with the socket type that will fit that type chip.

I think the best you can do with a conventional motherboard is 35w.
April 6, 2012 1:37:30 AM

Hi all

Thanks for feedback

To answer Proximon:

The use of the system:
Internet surfing
Audiobook listening
Internet tv and ripped DVD watching (I only rarely use my TV any more, as all Danish TV are streamed live, or can be seen later)
Dual screens
Light RTS gaming (like C&C generals, and the not-yet-published C&C Generals 2)
Very little FPS gaming, and I do not mind to play games in less-than-super settings
The PC will be turned on approx 12-14 Hours a day.
No video editing.

My intension is to use the onboard GPU in the i3; i5; (or even the i7?)

I would consider a laptop PC, or even an ultrabook, if power use where the only concern.
However, I like a desktop PC form factor better.
Mostly because of the desktop PC´s flexibility. I am tired of my 3 USB HDD, USB hub and their 4 separate power supplys taking up space under my workspace.

If I find my project impossible, I will drop the desktop and go for a laptop.
However, as the feedback from dankev shows, it seems possible with off-the-shell parts today, or, as tomskent says, wait a bit more for the new Ivy Bridge to be the brain of the system.

To geofelt: I did not know that there is no motherboard for the i5-2557 :( 
I had simply read somewhere, that it had surprisingly low power consumption.
April 6, 2012 1:41:05 AM

It's called a laptop. Why do you think they make different components for mobile electronics.
April 6, 2012 1:55:59 AM

If you're going to use the IGP, consider an AMD Llano based PC. The comparable Intel IGPs aren't in the same league as AMD's.

For low power usage:

Any FM1-socket mini-ITX motherboard (my personal favorite: ASUS F1A75-I DELUXE)

Low wattage FM1 CPU:
*E2-3200
*A4-3300 (some report ~0-5w idle, 10-15w usage, 20-25w heavy load)
*by comparison, A6-3500 (~38W idle/85 Watts heavy load)

Low latency, high speed DDR3 memory
Mini-ITX Case with power supply (or, get tiny platinum efficiency power supply, if they exist)
(Slim) Optical drive
SSD (OCZ Vertex 3, OCZ Vertex 4, Intel 520, Crucial M4)
2.5" Storage drive (if necessary, but replace with SSD if unlimited budget and if efficiency is most important)
April 6, 2012 2:27:01 AM

What a processor CAN pull and what it WILL pull under your usage is two different things. The whole point of modern power saving features is to minimize power consumption for any given load.

You seem to be trying to maximize your CPU power with a particular wattage in mind, and that doesn't strike me as the best strategy.

You should dial back on the CPU a bit, as you have absolutely no use for that much power. Instead invest in a good SSD and adequate graphics.

Those 3 external HDDs are going to take up power though.

Here:
http://www.xbitlabs.com/articles/cpu/display/amd-fusion...

On those drives, I have a different solution though. A separate NAS that will sleep when not in use.

Something like this, along with a laptop, is the best energy solution
http://www.newegg.com/Product/Product.aspx?Item=N82E168...



April 6, 2012 3:35:45 AM


Proximon wrote:
"Something like this, along with a laptop, is the best energy solution
http://www.newegg.com/Product/Product.aspx?Item=N82E168...[/quotemsg]"


Yep.
It was my first idea to combine a NAS and a laptop.
However, a NAS eats 35-50 watt or more.
Add the power use of the laptop!
And maybe a monitor, as I do not see myself being content with the small laptop screen

That’s why I am hoping to build an energy efficient desktop, where I can just pop in an extra HDD in when needed.

(I haven’t totally abandoned the NAS/laptop-compo idea yet. Been looking on QNAP 412, as it only uses 35 watt)
April 6, 2012 5:39:00 AM

I would definitely use this Motherboard for this kind of build.

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

At first glance this is a feature reach power hungry board like many other enthusiat class boards. It's not.

This board is designed to be and entusiat board but It has some huge power saving designs built into it.

Firtly it has SWITCHABLE GRAPHICS. Meaning you run you system completly off the Integrated graphics but when you are feeling like gaming start up you game and Your Power hungery graphics card is turned on just for your game and then COMPLETLY off agin when you exit the game. This gives you massive power saving while still giving you the ability to have high graphics performance. My freinds alienware laptop has this technology and it gets 8 hours running and 3 when gaming.

Second power saver is that it's it power circuits are laid out for max power saving with best performace as well.

3 you can connect this to your cell phone (bluetooth adapter not included) And as soon as your cell phone moved from you computer it immeditly falls asleep and wake back up when you return.

4 It comes with a program called smart 6. This program tunes your voltage automaticly to be power efficient and then automaticly changes it back when you need performance over power saving. Also you can adjust voltages and bios setting from windows with the new EFI bios and software it comes with.

Lastly it has the ability to charge usb devices without turning it'self on. So when you shut it off at night it will continue to charge your Ipod or cell phone without having to power the entire computer.

Here is the gigabyte read up from their site.

http://www.tomshardware.com/forum/341572-31-energy-effi...

I use a much older version of this board for My core 2 quad extream righ.

My set up is
4x500gb HDDs
4 sticks of 4 gig ram
2 CD roms
4 120mm fans
1 320 mm fan (IT"S HUGE)
and a 120 mm cpu cooler
Radeon hd5870
and a power hungery core 2 Quad EXTREAME CPU

Acording to my battery backup at Idel with all of the power saving features disable I draw and average of 165 watts. at full load over 600 watts When I turn all of the features on my idle stays below 100 wats to as low as 70 watts. and load is still 600 watts thanks go the graphic card. But it only goes up when I launch a Big time video game like crysis or star wars. With all of the features turned on I do not notice any performance impact at all.

Oh and this MB is 4 years old this new one I'm showing you has many power saving feature Mine does not have.


April 6, 2012 9:12:19 AM

:p wait for may/june and you will have a amd trinity apu based laptop that will use around 25w only.;)
April 6, 2012 4:08:17 PM

I imagine that the cost of electricity is high in Denmark. But the amount of power used by a pc without a discrete graphics card is really minimal.
It is hard to imagine that spending a lot on very efficient components will bring you any net savings.

Does in use 12-14 hours a day imply that the cpu is under 100% load, like in folding?
Or, does it mean that it is in standby, waiting for email or whatever?

If you set the pc tosleep using the S3 state(save to ram only) you will use minimal power from all components, and wake up is only a couple of seconds.

The current TDP of sandy bridge cpu's go down to 35w for the 2100T. Normally, the cpu will not use that amount, that is just the upper limit before thermal throttling will kick in. That will not change with ivy bridge.

Hard drives are 3-6w. A LCD monitor may use 1w in standby, and 25-50w in use. A 30" monitor may use 150W.
Motherboards will not use much either, in the absence of needing to power a discrete graphics card. The pcie x16 slot could draw up to 75w with a discrete graphics card..

For a small efficient pc, that will serve your needs, look at something like a G630T.

The integrated graphics is sufficient for HD movie playback and simple games.
Use a ITX motherboard.
A gold rated psu will be 10% more efficient if that is of value to you.

As to space, look at a small case like the Lian li Q08 which will hold 6 3.5" hard drives.
April 8, 2012 6:07:40 PM

Hi all

Thanks for all your input.
It has giving me a lot to think about.

I just found this (2 years old) artickle:
http://www.tomshardware.com/reviews/25w-performance-pc,...

I do not know why I have not found it before...
I think it definitley nails the combination of a laptop & NAS
The laptops I have testet, used between 20-30 watt even on a fully charged battery. Even the cute MACBOOK AIR uses 15-18 watt when connected to an outlet. (That is including the screen, I know, as the system in the article do not).

But sadly, it does not completely answer my dreams: I do not want to build a desktop based on 2 year old teknology.

The last day or so, I have been looking on boards with the processor pre-mounted (to se if I could find the laptop-based i3 and i5 on any of those). However, the only energy efficient systems I find here are with the "as-funny-as-slugs" netbook ATOM processors.
As I wrote, I tested a MACBOOK AIR, and it runs an I3 laptop processor at only 17 watt. You can even get an i5 processor on an AIR. It would be nice with this kind of power on a pre mount energy efficient board.


April 8, 2012 6:44:10 PM

The article used a i5-661 cpu chip, a chip with a tdp of 87w.
Yet, it met your requirements. That is because a chip will pull the max power under 100% load with perhaps some sort of overclock.
The 2100T has a tdp of only 35w, so in actual usage, you should do much better.

They used a M-atx motherboard which is larger and more power hungry than a ITX motherboard which is smaller.

They used two sticks of ram. You could use a single stick of up to 8gb without compromising performance. Not much savings though.

If your storage space is not too large, a SSD consumes very little power.
If a ssd is too small, look for a 2.5" laptop drive like the WD scorpio blue.

In reality, any lcd monitor will consume 50w or so when turned on, but <1w when in standby.
It would pay you to search first for a small efficient monitor.

To go even more efficient, look for a laptop. Their screens are designed for power savings.
To get large amounts of storage, you could use an usb3.0 connected nas server box.
June 14, 2012 1:45:43 AM

Have you seen these very low power computers? (6W total and up for just the CPU box)
http://www.environmentalleader.com/2008/10/14/top-10-lo...

And 4 watt monitors, but the site seems to be very out of date (Oct 2011???)
http://fit-pc.co.uk/7_USB_TouchScreen_Monitor--product-...

We live on a boat and a friend on another boat showed me me his system back in 2007 that drew about 1 Amp on 12 to 14V. IE 14W total for a complete system with monitor and CPU box. My memory of it was that his had like a 14" monitor.

My 15.6" laptops draw more like 3 to 5 Amps on 12V. But, my ASUS UL50V, is a little better. I am beginning to Google around for what I can find, with hopefully a 16" screen with 1300 x 800 or better resolution.

Dave & Janet
!