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I have a small single board computer. According to the manual the came with it:

  • when powered by a 5V ATX power supply, average consumption is 1.90 A (9.5 watts)
  • when powered by a 12V ATX power supply, average consumption is 0.07 A (0.84 watts)

So the board uses 9.5 watts for 5V operation and .84 for 12V operation. Does this sound right to anyone else? Why would the board use 10x the power at a lower voltage. Plus, does <1 watt for an embedded Intel Atom processor 1.6 GHz single-core (N270) sound correct?

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Take a look at Ryan's comment here. –  AndrejaKo Mar 13 '11 at 3:45
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Boards often take a mix of 5V and 12V. Are you sure it doesn't need both? If it uses a 4 pin molex connector, they provide both voltages. The power consumption would be the sum of both. It appears some newer boards take only 12V and have an on-board converter to provide lower voltage.

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Looks like you're right. It seems they nailed it at electronics. –  AndrejaKo Mar 13 '11 at 3:42
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First step would be to get newest version of the manual and see if they accidently added an extra zero to the 12 V current. As far as I know, latest Atoms use 7 W, so there's no way it would work with less than one watt.

As for the difference between power consumptions, there could be seeveral reasons. For example its 12 V power supply could have higher efficiency regulators installed than 5 V supply.

It could also for some reason need voltage higher than 5 V (USB port power supply maybe?). In that case, it would need to boost voltage and then to decrease it, which would use up some power. Still, to me even the 1.1 W difference (if I'm right and they meant 0.7 A) between 12V and 5 V looks a bit big.

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