Low cost 4 HDDs NAS

evlo · Post by **evlo** » Mon Jan 04, 2010 6:07 am

I'm going to build low cost NAS with 4 3.5HDDs and system on USB or 2.5HDD

my idea is to use custom case (about 50 USD in my country), johnstown, industrial 230v to 12V 9A with 30A startup max power suply (25USD in my country) and some scrap parts i have (ram, USB flash disk for system).

Main question is if the system will boot or wake hdds from sleep? I want to use board's integrated power supply for better(lower) power consumption. Or is there some power supply that only needs 230V input with really good efficiency i can use with johnstown or similar ultra-low-power-consumption-board?

Idea is that motherboard let 12V from external power source pass to molex. And hdds will use mainly 12V when spinup. But i'm not sure about this.

boost · Post by **boost** » Mon Jan 04, 2010 7:43 am

Here are some power consuption figuers for hard drives, startup and idle and more:
http://www.xbitlabs.com/articles/storag ... html#sect0
Four of these hard drives on startup need 3.5-4A on +5V and 5.6-10.8A on +12V.
I don't know if I read your figures correctly, 30A startup COULD work, but you have to read the specs for both power supply and hard drive carefully. You have to make shure that the mainboard can feed 4A on +5V, too.
Alternativly, you can get an efficient Seasonic OEM model pretty cheap:
http://geizhals.at/eu/a263737.html

evlo · Post by **evlo** » Mon Jan 04, 2010 8:37 am

Thank you for that link with 5V consumption data.

How much more power do you think will this 350W Seasonic use? I think that awerage power ussage of mb will be 12W and harddisk probably 8-12W. (i will be running them in pairs so i thing two will be sleeping all time).

boost · Post by **boost** » Mon Jan 04, 2010 9:52 am

The drives idle between 3.9 and 7.9 watts, that's roughly 16-32 Wats for four. In a very low power system I would estimate idle power between 30-46 watts.
Getting an estimate for the power supply figures is pretty hard since the sytem idles so low and most test don't bother with efficiency at or below 20% of the PSU's rated output.
I found three test of similar Seasonic power supllies on SPCR:
380 watt retail unit:http://www.silentpcreview.com/article753-page1.html
330 watt OEM:http://www.silentpcreview.com/article596-page1.html
400 watt OEM:http://www.silentpcreview.com/article261-page1.html
Efficiency for very low output seems to be about 65%. That puts AC power at about 46-71 watts.
A highly effiecient external power adapter with the integrated DC/DC on the mainboard can reach an effiency of 85%. That puts AC power at 38-54 watts.
All these numbers are only estimates! I don't know how efficient the industrial 230v to 12V unit you mentioned actually is.

boost · Post by **boost** » Mon Jan 04, 2010 10:17 am

I did a little research, I believe you're talking about this board:
http://www.intel.com/products/desktop/m ... erview.htm
The tech specs PDF (http://www.intel.com/support/motherboar ... 030300.htm) lists SATA interfaces page 19 one 1X4 (molex) power connector rated at 5V 3A and 12V 1.5A. Two drives would be pushing it, Idon't thinl it will work with four.
I would recommed a standard power supply like the Seasonic or a Pico PSU with an external power brick.
I found a helpful tip to get this board to work with raid controllers:
http://communities.intel.com/message/78 ... .node5COMS