Does 2GB RAM use more power than 1GB?

fkj · Post by **fkj** » Mon Aug 17, 2009 8:30 am

Looking to build a NAS and SqueezeCenter server with minimum power consumption when idle. Have my eyes on a D945GSEJT Atom board. Needs some SO DIMM RAM, but will 2GB use more power than 1GB, and how much more? I am sure the server will do fine with 1GB, but if I later want to use it for more demanding stuff, 2GB would be nice.

~Frank

lodestar · Post by **lodestar** » Mon Aug 17, 2009 11:02 am

The amount of power RAM uses depends on what it is doing, but the worst case scenario for 1Gb->2Gb is around 1.5w max.

Edit: Sorry left out the decimal point. The 1.5w is calculated from a statement on the web which was based on DDR2 533 speed.

lm · Post by lm » Mon Aug 17, 2009 11:19 am

2 sticks of RAM uses 2x as much as 1 sticks of same spec RAM.

But if you compare 2GB/stick to 1GB/stick, the difference is usually smaller.

The driving voltage for the memory module also matters, some modules need more juice to run. These are listed in the module specs.

In any case we are probably talking about 1W of difference, so it should be the least of your concerns.

lm · Post by lm » Mon Aug 17, 2009 11:20 am

lodestar wrote:The amount of power RAM uses depends on what it is doing, but the worst case scenario for 1Gb->2Gb is around 15w max.

15W

Where do you get such massive numbers from?

I've 4x2GB DDR2 800MHz ECC RAM in my machine, and the whole system idles at 110W. Rest of the specs in sig. The RAM probably uses <10% of my total power.

[Mod comment: he corrected himself and put 1.5watts (1 1/2 watt).]

fkj · Post by **fkj** » Mon Aug 17, 2009 11:31 am

The D945GSEJT only have one SO DIMM slot, so I am comparing the power consumption of 1GB vs. 2GB in one slot and with the same specifications (MHz, voltage,...).

Will 2GB use 1W more? I am aiming at a system around 13-15W so every watt counts

~Frank

lodestar · Post by **lodestar** » Mon Aug 17, 2009 12:13 pm

I have corrected my earlier post. Based on a source on the web you are looking at 1 - 1.5w max, and significantly lower than that in standby.

There is a product technical document by Intel which shows their calculated power consumption figures for minimum and maximum load configurations. This is a PDF which can be downloaded from http://download.intel.com/support/mothe ... 2001us.pdf. With 2Gb RAM Intel reckon lowest possible power consumption is 12.8w, with a 'fully loaded' configuration drawing 42.04w (see pages 55/56).

ame · Post by **ame** » Mon Aug 17, 2009 1:29 pm

I am aiming at a system around 13-15W so every watt counts

What are your system specs so far?
This seems so lowwww , I was gonna guess Atom? but sodimm threw me off.

lm · Post by lm » Mon Aug 17, 2009 2:43 pm

1W * 24h/d * 365d/y is less than 9kWh a year, so around one euro per year.

Are you running this device off the grid or what?

fkj · Post by **fkj** » Mon Aug 17, 2009 11:22 pm

Ok, so it's about 1-1.5W, thanks.

Specs will be:
- Intel D945GSEJT (Atom N270) - 11-13 W (with RAM)
- 1-2GB SO DIMM 533HMz
- WD Caviar Green 15EADS 1.5 TB - 3.5W
- Power brick with ~90% efficiency - 1.5 W
- And maybe an Intel Z-U130 SSD 2GB as boot device (this only adds to the power consumption, but it will allow me to keep the entire HD as one partition for data)

I have seen a similar build which draws around 14W, hence I am aiming at <15W.

Preferably I want the system to suspend to RAM or even to disk, when not in use, but if I can not get that to work probably, I want it to be as low power as possible when idle.

lm, I will be running it on the grid, but your question makes me what to run it entirely on solar power.

However in Denmark that may not be possible in the winter. Also, setting it up will cost a lot more than several years on grid power.

~Frank

lm · Post by lm » Tue Aug 18, 2009 12:43 am

Chances are, you might get more than 1W savings in some other part of your energy usage than the computer?

Do you have any incandescent or halogen lights?

fkj · Post by **fkj** » Tue Aug 18, 2009 1:59 am

It's not just the cost of the electricity. +1W is ~7% more heat in the case, i.e. one step closer to not being able to run it without a fan.

Also 1W is the equivalent of having an extra energy saving light bulb running for 2-3 hours each day. Again not much, but it all add up.

I think the biggest incitement for only having 1GB is that, with 2GB I will not be able to suspend to disk with a small 2GB SSD used as system disk.

~Frank