What are the costs and benefits of using 12V-only motherboards?

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According to my research, it sounds as though power efficiency concerns in recent years have driven some hardware manufacturers to create different power supplies and motherboards which are "12V-only". That is to say, power supplies have been created to supply 12-volt power exclusively, directly to the motherboard. Motherboards, in turn, have been built or modified specifically to receive 12-volt power only and convert it into usable power for the various 12-volt, 5-volt, and 3.3-volt hardware components within the single computer associated with that motherboard.

From a technical perspective, what are the costs and benefits of adopting such an approach for powering a computer?

What about from an economic perspective?

Is this type of hardware available to the mainstream?

nairware

Posted 2012-08-20T03:30:08.947

Reputation: 405

Question was closed 2012-08-20T16:23:36.980

I'm guessing this is mostly a cost-reduction strategy, since extra voltages in the PS cost money. But it's less efficient to down-regulate 12V to 5V than to generate the 5V directly, so it's likely not an energy-saving strategy. – Daniel R Hicks – 2012-08-20T03:45:57.807

OTOH with the power drawn by modern desktop CPU's (50W is typical) using a 12V supply means that you only have 4A currents; a 5V supply would need to provide 10A. That in turn requires thicker cables. Also, the CPU needs 1.3V or so, which means you need a downregulator anyway; might as well use a 12V->1.3V one. – MSalters – 2012-08-20T14:09:54.953

Answers

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For Mini-ITX and other small form factor boards, the advantages of having onboard power regulation are cost reduction and form factor.

From a cost perspective, the price delta for two equivalent boards with/without onboard power is typically less than $10. Compared to the cost of even the least expensive picoPSU, that be a significant savings.

Eliminating the need for a full ATX connector on the board also allows the designer to be more flexible in component placement and reduce the Z-height of the board to newer Thin-ITX standards.

This is even more important for smaller form factors such as 3.5"/ECX and Pico-ITX, where adding a discreet power supply negates the miniscule packaging of the board.

The major disadvantage is the inability to use wide-input regulators (unless implemented onboard, as with the Intel DN2800MT "Marshalltown" board which can handle 8v-19v), and the extra bulk of an AC/DC brick instead of a straight AC/120v cord. Of note, some of the boards designed for desktop-class CPUs utilize a 19v adapter instead of 12v.

Toneloc427

Posted 2012-08-20T03:30:08.947

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Asked: 2012-08-20T03:30:08.947

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Active: 2013-09-11T11:24:53.597