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 Post subject: How much current does RAM draw?
PostPosted: Thu Jan 17, 2013 8:58 am 
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Joined: Thu Jan 17, 2013 8:48 am
Posts: 7
Hi :-)

I am about to build a new fanless PC with a small 80 Watt PSU (rated at only 60 Watt without forced air flow) in an HD-Plex s5 case. The motherboard will be the Asrock z77e-itx, and the CPU will be the i5-3570k. I will not install a graphics card but instead use the PCIe slot for a card for my sound interface. I still have to choose my RAM, and I would like to gather some information to inform my choice.

Is there a noticeable power saving in going from 1.65 to 1.5 to 1.35 to 1.25 Volt?

Will a 8 GB module with the same rated voltage draw twice the current compared to a 4 GB module?

Thanks :-)
Immanuel ♪♫


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 Post subject: Re: How much current does RAM draw?
PostPosted: Mon Jan 21, 2013 12:35 pm 
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Joined: Thu Jan 17, 2013 8:48 am
Posts: 7
Ok, any experience with RAM's power use is welcome :-)


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 Post subject: Re: How much current does RAM draw?
PostPosted: Mon Jan 21, 2013 11:53 pm 
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Joined: Tue Oct 23, 2012 8:13 am
Posts: 53
Location: Suisse Romande
You can find some numbers and information on http://www.pugetsystems.com/labs/articl ... ge-RAM-150 They say using low voltage RAM can reduce peak power consumption by 2-3 Watt per stick.

As far as I know 8 GB sticks use memory chips produced at a newer process (30nm?) and might actually use less power. Samsung claims that "By applying industry-leading 30nm technology, Samsung DDR2/DDR3 uses up to 47% less power than 60nm memory."

I do not know how much power the 77W CPU uses at start up, but combined with the other components and any USB peripherals it might reach 80W. Try to get some numbers to make sure your PC will actually start. (I think someone at SPCR answered this already, but I can't find it right now.)


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 Post subject: Re: How much current does RAM draw?
PostPosted: Tue Jan 22, 2013 11:11 am 
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Joined: Sun Jun 17, 2012 10:51 am
Posts: 70
Location: USA
I just got some of the Samsung sticks that are 1.35V. Once I get them installed and OC'd to my liking, I'll let you know what kind of temp differences I'm seeing.


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 Post subject: Re: How much current does RAM draw?
PostPosted: Tue Jan 22, 2013 8:55 pm 
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Joined: Sun Feb 06, 2011 11:19 pm
Posts: 78
Location: North of the 49th parallel
I've made some measurements on a complete system, with one and two DIMM's installed.
Setup:
CPU: Intel Pentium G2120
MB: Intel S1200KPR
RAM: Kingston KVR133D3E9SK2/16G, 16(2X8)GB DDR3-1333 ECC, 1.5V
System power:
1. System on, after 10 minutes idle on the desktop, 2 modules:
19.5V*1.01A=19.7W
2. System on, after 10 minutes idle on the desktop, 1 module:
19.5V*0.95A=18.5W
3. System running Prime95, 2 treads, blend test, 2 modules:
19.3V*2.33A=45W
4. System running Prime95, 2 treads, blend test, 1 module:
19.3V*2.15A=41.5W
According to the #'s, the DIMM power draw is up to(processor IMC power is included) 1.2W idle and 3.5W under load.
IMO, if you're looking for the lowest power memory, go with the "30nm" Samsung.


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