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PicoPSU vs external DC power brick

Posted: Fri Jun 07, 2013 7:35 am
by matchu
Title says it all

Debating getting an mITX board with a direct-to-DC power connector vs a more "standard" motherboard that I can attach a picoPSU to.

Purpose is home file server. Thinking of either an atom or celeron-based board. One hard drive.

Question: Which one is more efficient at those sub-100W loads?

Thanks!

Re: PicoPSU vs external DC power brick

Posted: Fri Jun 07, 2013 11:59 am
by fwki
PicoPSU's also use an external AC/DC brick, so it's all about the brick wrt to efficiency. You'll have more flexibility to choose your own brick with a picoPSU rather than a bundled brick with a MB. But with a typical picoPSU your MB is subject to the quality of the 12V brick output since the picoPSU just passes it through. Mike had a good article here a while back comparing picoPSU's to the Electrodacus' Winmate...http://www.silentpcreview.com/Winmate_DD-24AX

Re: PicoPSU vs external DC power brick

Posted: Fri Jun 07, 2013 10:34 pm
by QUIET!
It makes no sense to buy a picoPSU and use a crummy power brick.

Its relatively easy to find an appropriate V rated brick (I believe its an Energy star rating which may be recently defunct), then add the connector of your choice and you're ready to go with high efficiency guaranteed.

The down side of an integrated motherboard with PSU and a 19v brick is that there is no guarantee that you can reuse your brick for anything.

I consider a PSU to be something that will hopefully survive an upgrade cycle or two and I don't see anything coming that would obsolete the current ATX spec.

So if you are planning on a computer that will be in use for 5+ years without major upgrade, they both can make sense. If you think 3 years and then upgrade, picoPSU makes more sense.

Re: PicoPSU vs external DC power brick

Posted: Sun Jun 09, 2013 6:09 am
by matchu
Thanks for the replies

So then, it doesn't really matter what PicoPSU I get, as long as it 1) has the connectors I need and 2) can support the wattage that I need? And the more important thing is to get an efficient power brick?

Re: PicoPSU vs external DC power brick

Posted: Sun Jun 09, 2013 9:14 am
by QUIET!
That's my opinion.

Dell made some powerful 12v bricks with V rating and they can be found cheap.

I see too many people complain about the bricks that the picoPSU guy bundles but they may be fine for very low power systems.

Re: PicoPSU vs external DC power brick

Posted: Sun Jun 09, 2013 11:58 am
by matchu
Thanks, Quiet!

I guess my other question, then, is that for DC-powered motherboards will any power brick theoretically do? As in, I can get a laptop brick and as long as it fits and has the correct power rating as specified by the MB, that's fine?

Re: PicoPSU vs external DC power brick

Posted: Sun Jun 09, 2013 5:31 pm
by alisonc
matchu wrote:Thanks, Quiet!

I guess my other question, then, is that for DC-powered motherboards will any power brick theoretically do? As in, I can get a laptop brick and as long as it fits and has the correct power rating as specified by the MB, that's fine?
Yep, a 19V brick is a 19V brick. Do note, though, that some bricks have some 'inteligence' in it that won't work unless it's plugged into the right brand of laptop.

Re: PicoPSU vs external DC power brick

Posted: Sun Jun 09, 2013 11:41 pm
by QUIET!
The voltage has to be correct and the current has to match or exceed your actual load.

Most laptops use wimpy 60-90 watt bricks because their hardware is designed to be low power.

The 12v Dell bricks I mentioned were for ultra small form factor desktop PCs with more standard desktop style components and higher power requirements.

If you want a high performance system or don't want to spend big on low power hardware, you are going to need power and that might be hard to find at 19v or whatever it needs.

One other thing, PCs have various assorted 12v peripherals so when you use a different voltage brick, all the 12v has to be generated by a step down dc-dc switch mode power supply while a 12v brick can feed power directly to a PCIe 12v connector for example.

I was considering using a desktop board with desktop CPU and a Radeon 7790 with a picoPSU, I'm almost positive a setup like that is impossible with a 19v setup.

I cheaper out and modified a 255 watt OEM PSU (80+ gold rated) to power it instead but I have it in a microATX case, if I was going small picoPSU might have been my choice (but I found a cool OEM SFF PSU that was cheap and 80+ gold rated too and I want to do something with it).

Re: PicoPSU vs external DC power brick

Posted: Mon Jun 10, 2013 1:47 am
by Cistron
QUIET! wrote:The 12v Dell bricks I mentioned were for ultra small form factor desktop PCs with more standard desktop style components and higher power requirements.
Indeed. If you seach for Dell DA-2 you'll find lots of information here on the forum.

Re: PicoPSU vs external DC power brick

Posted: Mon Jun 10, 2013 6:27 am
by matchu
I will look up that dell brick, but as my potential purpose, I was thinking this could be used for the Intel DN2800MT (atom-based board) which a lot of people note draws less than 20W. The power specs ask for 19V DC in via an external brick.