Should I go with one 4GB or two 2GB sticks of RAM for my new home server build.
Did anyone measure difference in power consumption between one and two RAM sticks configurations?
Also, how much is dual channel really important?

It depends on what you are going to have running on your server, and if you really care about a difference of 1-2 Watts, which is most likely the difference between 1-stick and 2-sticks of RAM (unless you are going for high end RAM that is typically factory overclocked and certified from slower types of RAM and can use quit a lot more power than standard 1.5v 1,333-MHz DDR-3).

If your server is simply going to be a file-server then I doubt it would make the slightest amount of difference going dual-channel, if however you are going to be running a file-server that is also a web-server or used by many clients, or is running any server-side software then you will most likely want to use an extra 1-2 Watts of power by going dual channel to avoid performance bottlenecks.

Anyway, 1-2 W is not worth talking about unless you have also tackled other things that will make a far larger difference to your servers power consumption, e.g. CPU, Motherboard, Chipset, HDD's, and importantly PSU.

For example you could save 1-2 Watts of power by using Wired Gigabit Ethernet rather than N150/N300 Wireless, and that is not a joke, I have seen USB Wifi use 2-W when Idle.

So in summary: Performance wise - it simply depends on what you are using your server for (a home file-server, 1-stick of RAM will be just fine). Power wise - its of less importance than many other choices, but if it is a new build then 1x 4GB stick of RAM is also going to be a little cheaper than 2x 2GB sticks of RAM, and as mentioned you wont need anything more than 1.5v 1,333 MHz DDR-3, although I would suggest buying good quality branded RAM (Kingston, Crucial, Corsair etc that are fully tested and have long warranties).

Could you tell the forum what else your server is going to be made of.? We can make suggestions on parts that will also be low-power, quiet, fast-enough and wont break the bank, most people building home-servers totally over-spec the machine and end up with something that is more expensive, uses more power than needed and is noisier than it should be for its job.


Andy

Thanks for the reply, I was abroad for a few days and couldn't reply earlier.

I am building home media server, and my plan was to buy either AMD E350 or Intel G530. I'd like to have 6 SATA ports for future expansion, but I can live with 4 as well. Some H61 boards have 6, but they are a bit more expensive, which makes the price of G530 + mobo almost twice as the price of AMD E350.

Regarding power supply I think that most efficient PS I can find in my country is Seasonic S12 II 380.

For most applications, the performance difference between one or two stick is slight at best.
If you're considering an E-350, you must not care about such differences because the CPU is slow and the difference is not slight.

I doubt you can't find a more efficient PSU.
If that's true and you're not going to run several 3.5'' drives, you should get a board which can use an AC/DC brick instead of an ATX PSU. If you care about power consumption, the PSU will make a lot more difference than an extra RAM stick. There are Sandy Bridge and Atom boards which use a brick but the Atoms have only 2 SATA ports (otherwise the nicer models consume less and are as good as an E-350 for server duty).

How about splitting the difference and using two sticks of 1.35V SDRAM? Samsung is now offering DDR3 SDRAM produced at their 30nm process that is pretty cheap and runs at 1.35V. This memory is also lower profile than the typical module which could help with heatsink clearance and perhaps air circulation.

If you go to Samsung's memory product page, you'll find power consumption listings for each memory module under the specs submenu. A 2GB stick of DDR3 consumes 1.36W and a 4GB one consumes 1.65W. The difference then between 2x2GB and 4x1GB is 1.07 watts.

After going through the specs of the various memory modules, I picked up a few interesting things: 1) laptop SODIMMs consume slightly more power than their desktop counterparts (e.g. for 2GB modules, 1.49W vs. 1.36W) and 2) 40nm DDR2 consumes less power than 30nm DDR3 (again using 2GB modules, 1.03W vs. 1.36W).

I recently upgraded from 2x2GB@1.65V to 4x4GB@1.35V* and my power consumption went down a couple of watts, so this low-voltage stuff is definitely good.

*Curiously, the SPD says the voltage should be 1.28V, not 1.35V. I can't tell what it's actually running at.

I use G-Skill Sniper in most of my systems, they are 1.25v but not all motherboards support that voltage. They run fine at 1.35v or 1.5v as well of course. They have a goofy looking heatsink but are quite cheap in my area.

These are about all power supplies that are available in my country. I don't see any other low wattage PS that is more efficient than Seasonic S12.

http://itsvet.com/proizvodi/seasonic/co ... oducer/725

My plan is to have up to 4 hard drives, I am not planning to expand further for at least 2-3 years.

A 380W PSU is total overkill for that system spec.

My Server has an old 95W CPU, 7x HDD's, a hardware RAID card and a dedicated graphics card (ancient PCI card), that machine has never hit 200W of power usage.

Ideally you should use a power brick and a Pico PSU as they are a lot more efficient at such low loads.

If you ended up with an E350 it is single channel ONLY, so the question is moot about whether to use 2x DIMM's, but they are not particularly fast, how much of a difference you will see vs a proper desktop CPU I don't know, but they are very efficient.


Andy

I hope there is another shop in your country. If not, you can always order a part abroad.
In general, low-wattage power supplies are more efficient but there's an important exception to the rule: there aren't many reasonably efficient standard power supplies rated for less than 400W and the most efficient are rated 500W or more.

The Seasonic you're looking to buy would waste 12W or more. All power supplies waste something, but the efficient ones don't waste nearly as much. Compared to that, any saving you might achieve by focusing on your RAM would barely be significant.


If you're going to have so many drives, note that your choice of drives could also have a much larger impact on power consumption than your choices regarding RAM.

Many thanks for all the input. It does seem that number of RAM sticks is largely irrelevant.

Here is what one review states about that Seasonic:
"1. EFFICIENCY was excellent. At the super low load of just 21.6W, it was already 65.4%. This compares favorably with the Corsair VX450W's 61% efficiency at the same power load. Most PSUs we've tested barely reach such efficiency at double the power output, but with the S12II-380, by ~40W, efficiency had reached 76.3%. The benchmark 80% efficiency was seen at about 70W. The peak of 84% was centered at about 200W, and >80% efficiency was maintained to full rated 380W output, as expected of a model certified 80 Plus."

Any recommendations about PicoPSU that would be well suited for this build?

Excellent would be more like 90%. We seem to have different standards. Or maybe that's simply progress: you quoted a review that's nearly 5 years old.


I'm not sure I would recommend a pico if you're going to have that many drives (presumably filled with valuable data). Others have used a pico with a handful of drives but the actual power demands of the particular drives you want to is what will tell you what pico/brick you need or indeed if you shouldn't even try to power that server with a pico. Some drives need quite a bit of power when they spin up and I don't think we should assume your board or controller will have staggered spin-up.

Both of those PSUs are quite old today. If you have one lying around it could be used, but buying one new today.. With a picoPSU and a good brick you can have an efficiency in the high 80s. A modern ATX PSU like the Seasonic X-400 wouldn't do quite that well but would of course be way better than an old Seasonic S12. They are not cheap though.

I use a picoPSU-90-XLP and a nice Mean Well AC-DC adapter for my file server right now (details in my signature). But finding a good AC-DC adapter can be tricky. Also, as HFat points out, a regular PSU will give you more headroom. With a picoPSU you will need to take care how many HDDs you use and how much power they need.

Oh well. What about this one:

http://geizhals.at/671537

Let's say I lose 20W per hour due to inefficient power supply. That's around 175 KWh per year, which translates into around 7 Euros cost difference per year, which is not so bad. Investment in some highly efficient, yet expensive power supply would take many years to pay off.

This one looks more promising: http://geizhals.at/eu/680221

Your electricity is cheap. Maybe that's why they don't bother selling decent PSUs.

I found also this supply in one of the shops in my country:

http://www.plugloadsolutions.com/psu_re ... Report.pdf

Seems OK to me, especially considering it's just around 40 Euros.

RE: PSU requirements and HDD power usage.

PicoPSU's are available in 160W flavour @ 12v DC input, or at 120W flavour that would allow you to use a 19v Power brick, this is their "wide input" version that allows 12v - 25v input.

Either one of these would be overkill for an E350 system with 6x 7,200rpm HDD's, let alone 4x low power drives, so the PicoPSU option is still available to you, it is more expensive than a standard ATX PSU, but it will be more efficient, although how long it will take to pay back the extra cost by spending less on electricity I cant answer, but so long as you got a "fan-less" power brick the Power input would be silent (excluding possible coil whine).


Andy