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 Post subject: Minimum i5 power consumption under load (laptop project)
PostPosted: Thu Jun 09, 2011 3:07 pm 
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Joined: Thu Jun 09, 2011 2:56 pm
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Does anyone have any stats for what the lowest possible power consumption is for an i5 under full load? I've been toying with the idea of building a custom laptop out of desktop parts and I was hoping to use a picoPSU-120, but it seems like all the i5 reviews show that Sandy Bridge comes awfully close to 120W max or exceeds it (see, for example, http://www.hardwarecanucks.com/forum/ha ... ew-20.html).

I don't need any fancy graphics, integrated will do just fine. i3 won't cut it because I need at least four cores for parallel compiling. Some reviews seem to indicate that Clarkdale is more power efficient than SB, but that seems strange. On the other hand, if Clarkdale really is lower, then I'd be OK with that. I know there are the S and T parts, but they seem much more expensive (especially 2500T) whereas I can get a i5 2400 for $150. Could I undervolt to get reliably around 100W under full load for hours? Do I need the 2500K for that, or will any i5 with the appropriate motherboard do? Also, n00b question: does undervolting "damage" a CPU the way overclocking does?

I'm open to AMD, if anyone knows of a way to get the wattage down (main rig is an X6 and I love it).

EDIT: Also, is there generally a difference in power consumption between mATX and mini-ITX boards if the CPU and GPU are the same? Can anyone recommend a "low power" motherboard, if such a thing exists?


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 Post subject: Re: Minimum i5 power consumption under load (laptop project)
PostPosted: Fri Jun 10, 2011 6:09 am 
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My i5-2500K system, powered by a 150W picoPSU seems to max out at slightly above 110W AC. This is with 4 x Prime95 and FurMark and the IGP slightly overclocked.

Intel has traditionally been king of power efficient boards, MSI is also good. Asus and Gigabyte less so.

Lowering the voltage does not damage the CPU, but can like overclocking lead to instability.

_________________
Main: ASRock B85M-ITX | i3-4330 | 16GB DDR3 | Intel 730 240GB | HDPLEX H1-S | picoPSU | No moving parts | Idle 13.9W
HTPC: ASRock H81M-ITX | Pentium G3420 | 4GB DDR3 | Intel 520 120GB | HDPLEX H1-S | picoPSU | No moving parts | Idle 11.2W
Gaming: Intel DH77EB | i5-3570K | GTX 750 Ti | 16GB DDR3 | Intel 520 120GB | TJ08-E | G-360 360W
Server: Intel DH77DF | i3-2100T | 4TB+3x3TB | picoPSU | Idle 24W AC


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 Post subject: Re: Minimum i5 power consumption under load (laptop project)
PostPosted: Fri Jun 10, 2011 9:55 am 
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Joined: Thu Jun 09, 2011 2:56 pm
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Vicotnik, thanks for the tip, I didn't realize that picoPSU made a 150 W version. Looks like there's also a 160 W: http://www.mini-box.com/picoPSU-160-XT. How hot does it get, I wonder? By the time I get the external brick, maybe it would be easier just to go with a regular PSU, but that would require a bit more wiring. I was planning on using a solar panel charge controller to switch between the battery and the AC adapter, which has 12 VDC pos/neg terminals for the "solar panel" (i.e., adapter) and the same for the battery (http://www.amazon.com/HQRP-Battery-Cont ... 234&sr=8-1). Hopefully the switching speed is fast enough.

I forgot to mention that I'm going to have to power a screen, as well. I know that new LCD's can get down around 10-20 W depending on size. Any suggestions for that?


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