A thought on PSU form factors...

LjSpike

SFF Lingo Aficionado
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Mar 20, 2017
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One thing I dislike most with current PC components is PSU's - They do their job fine, but the two most common form factors, ATX and SFX seem so inefficient... TFX is a nicer one but seems far more uncommon.

ATX and SFX both go for a shape which is quite close to a cube, which doesn't seem to make much sense, unless you mount them on their size, they can be a relatively notably increase to the width of the PC.

I just thought I'd share a set of dimensions I'd come up with quickly in SketchUp, first I'll share an image of an ATX in the space that I was thinking of though.

As you can see, it contributes a fair bit to width, obviously I've not been incredibly tight on clearance, it still fits within parameters I was designing too, but really, it uses up a large amount of width and doesn't make use of reasonable amount of length of the case.
The alternative set of dimensions would be a cross section of 100x75mm with a depth going up to 250 or even 300mm
It then fits far more nicely beneath where the GPU sits. If a concern about aifow existed, well you could put fans on the side.

I wonder what your thoughts are on it?
 

HansWursT619

Trash Compacter
Feb 22, 2016
45
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An SFX PSU with its width of 125mm should not add much, if anything, to a standard height GPU.
The Problem with TFX and other shapes is the fan. It is difficult to cool a PSU quietly with fans much smaller than 80mm. But luckily efficiency is getting to the point where we can have very high powered fanless design :)

We actually have quite a good selection of formfactors in my opinion and something fits any purpose. You will just have to make a compromise in either size or noise.
 
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jeshikat

Jessica. Wayward SFF.n Founder
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Feb 22, 2015
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The SFX spec actually allows for a 100mm width x 125mm depth configuration instead of the 125mm width x 100mm depth normally seen on consumer SFX units these days:



I believe some OEM cases used to use this version, but it's basically nonexistent today.
 

LjSpike

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Mar 20, 2017
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That's a shame. I feel like less width on a PSU fits better for desks. Height I don't feel is really ever to hard to accompany, but width and depth can be...
 
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LjSpike

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Mar 20, 2017
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That really depends on the case layout, I usually find PSU height harder to deal with.
Do you usually have the GPU directly connected to the motherboard or use a flexible cable so you can put it in a different position?
 

neilhart

Cable-Tie Ninja
Apr 18, 2017
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Do you usually have the GPU directly connected to the motherboard or use a flexible cable so you can put it in a different position?

I have built a fair number of systems from scratch and have used all of the common form factor PSUs at one time or another. My on going favorite is the Silverstone SST-ST45SF-G, a fully modular STX unit. This is tech that even feels good when you handle it.




But to respond to your query, I prefer to build systems with the GPU installed in the MB 16x slot. By choice, I focus on Mini-ITX and usually try to use AIO water cooling. Although I have had success with PCB riser cards, I have had issues with cable risers so I don’t go there anymore.

In the above system, the PSU takes air from the bottom and exhausts out the rear and there are 4 SSD/HDD just to the front of the PSU making excellent use of the available space.

Neil
 

jeshikat

Jessica. Wayward SFF.n Founder
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Feb 22, 2015
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Do you usually have the GPU directly connected to the motherboard or use a flexible cable so you can put it in a different position?

Personally I prefer to avoid PCIe extenders since they're finicky and it's questionable if/how they'll work in a few years once PCIe 4.0 lands.
 

|||

King of Cable Management
Sep 26, 2015
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Personally I prefer to avoid PCIe extenders since they're finicky and it's questionable if/how they'll work in a few years once PCIe 4.0 lands.

The last I heard (probably circa 2012-2013 from some public PCI-SIG slides of PCI-e 4.0 version 0.7), PCI-e 4.0 was capable of supporting up to two interfaces in the communications path. That would mean a single riser should be possible, with an interface at each end connecting to the board and connecting to the card.
 
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jeshikat

Jessica. Wayward SFF.n Founder
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Cool, but if the expensive 3M extender is the only one capable of PCIe 4.0 that would be annoying from a case designer perspective.
 
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LjSpike

SFF Lingo Aficionado
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Mar 20, 2017
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Some interesting thoughts.
I'll undoubtedly still look into a few STX PSU's too, Flex ATX seems to, just like TFX, be a bit on the uncommon side, which I just find a mighty shame...