Power Supply Why use an external PSU?

JosephEK

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I'm curious since it seems like a lot of people on this forum really like the external power bricks. What advantages are there over something like a standard SFX PSU? They don't appear that much smaller and you still have to find somewhere for it to go. I actually have the little adapter board, cables and 230W external PSU that powered my old Alienware X51. I could probably use it on some kind of integrated graphics build.

How does Kaby Lake's HD630 integrated graphics play games like Rocket League at 1920x1080p? If they're not good enough maybe I can wait for Ryzen APUs because I want to be able to use M.2 storage and I know of no mITX+ FM2+ motherboards that feature M.2 slots on front or back. I probably wouldn't even care if it was SATA as long as I can just have my drive directly on the board.
 

PlayfulPhoenix

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I know that many folks like external bricks since they can be kept off a desk - either in a cable channel, behind a desk, on the floor, etc. Helps to compact the computer that is on your working surface :)
 

zovc

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Jan 5, 2017
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The long story short, as I understand it, is that it's much easier to fit everything in there with the significantly smaller PSU. The boards themselves are about ~1/3 the size of a SFX power supply, and most all of them are fully modular.

You're also able to adjust the size of your external brick without necessarily needing to change your hardware.

I don't think Kaby Lake's HD630 would run Rocket League at 60fps in 1080p, but my impressions of integrated graphics are based on a mobile i5-5200U which admittedly surprised me with how well it can emulate up-scaled 3D PSP games, and an i7-4790K which struggles to run Resident Evil 5 at 30fps in 720p.

That said, integrated graphics simply cannot compare to a 750Ti and they definitely can't stack up to the new 1050/Ti. I have serious doubts that AMD's APUs will perform better than Intel's integrated graphics because Ryzen is already demonstrating worse single-core speeds and is struggling to put up with fast RAM overclocks. (Not to say the RAM issues won't get sorted out.) As I understand it, your single-core performance and the speed of your RAM are the two most important factors for how well your integrated graphics will run.
 

HansWursT619

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Feb 22, 2016
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If I desperately need the space on my table, so that an external PSU makes sense...
Why I don't just put the whole PC on the floor somewhere?

I think external PSUs are just for people who want the tiniest build possible. But I don't really see a good reason for it.
Maybe if you travel between only two places and have a PSU at both places?
 
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PlayfulPhoenix

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I think external PSUs are just for people who want the tiniest build possible. But I don't really see a good reason for it.
Maybe if you travel between only two places and have a PSU at both places?
That's actually an interesting use case i hadn't thought of before!

In any case, @zovc also has some good points/reasons. I think that, in general, most folks who use external bricks in their builds do it for a very specific reason or two that's pretty contextual to their own preferences or circumstances. But there's a lot of those reasons.
 

JosephEK

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Mar 6, 2017
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If I desperately need the space on my table, so that an external PSU makes sense...
Why I don't just put the whole PC on the floor somewhere?

I think external PSUs are just for people who want the tiniest build possible. But I don't really see a good reason for it.
Maybe if you travel between only two places and have a PSU at both places?
I guess I could see external PSU good for portable systems like for LAN parties and stuff. I mean the wire containing the power brick can be stored in a different pocket on your back-pack for example.

The long story short, as I understand it, is that it's much easier to fit everything in there with the significantly smaller PSU. The boards themselves are about ~1/3 the size of a SFX power supply, and most all of them are fully modular.

You're also able to adjust the size of your external brick without necessarily needing to change your hardware.

I don't think Kaby Lake's HD630 would run Rocket League at 60fps in 1080p, but my impressions of integrated graphics are based on a mobile i5-5200U which admittedly surprised me with how well it can emulate up-scaled 3D PSP games, and an i7-4790K which struggles to run Resident Evil 5 at 30fps in 720p.

That said, integrated graphics simply cannot compare to a 750Ti and they definitely can't stack up to the new 1050/Ti. I have serious doubts that AMD's APUs will perform better than Intel's integrated graphics because Ryzen is already demonstrating worse single-core speeds and is struggling to put up with fast RAM overclocks. (Not to say the RAM issues won't get sorted out.) As I understand it, your single-core performance and the speed of your RAM are the two most important factors for how well your integrated graphics will run.
If even low profile GPUs like GTX 1050ti or RX 460 are better than the best APUs then is there any SFF cases designed specially for them? The smallest I can find is Silverstone's ML09 which is 7 Liters volume.
 
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Grafite

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Feb 20, 2017
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If I desperately need the space on my table, so that an external PSU makes sense...
Why I don't just put the whole PC on the floor somewhere?

I think external PSUs are just for people who want the tiniest build possible. But I don't really see a good reason for it.
Maybe if you travel between only two places and have a PSU at both places?
My PC is like my phone in a lot of ways. I need it everywhere I go. However a PC is 50% larger when you start adding in a SFX PSU. The Sentry and Dan A4 are the smallest cases I know of that can house an SFX PSU. Both are significantly larger(than the S4) for nothing. I still need to carry around a power cable to power them. With an external brick almost nothing changes, there is a small hump in that power cord you still have to carry. But now your case is smaller and produces less noise and heat.

And I'm not the minority here either. Everyone with a laptop carries their laptop brick, same deal here. Everyone travels with a phone charger + brick and not just a cord.

Putting a PC on the floor is weird IMO. If you bought a nice case and nice looking peripherals, why would you put it on the floor? The floor also increases dust and particle collection.
 

thewizzard1

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Jan 27, 2017
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It's easier for me to fit one small PC and one smaller power supply module in my backpack than it is for me to cram one medium sized (for sake of comparison) PC instead.

Also, laptop bricks and their corresponding DC/DC solutions tend to be more efficient - Less heat means less prerequisite airflow, means smaller fans and reduced size
 

Lone

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External bricks are also completely silent (the good ones anyway), and being external they don't dump any additional heat into the case, which can result in a quieter system. I think external AC-DC adapters are a good option for low power builds. Once they start becoming larger than the footprint of the computer, I start to cringe. :) I just got a 120W 12V external AC adapter with a G-Unique DC-ATX, and I think it's size (155 x 69 x 36 mm) is still pretty good.
 

HansWursT619

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Feb 22, 2016
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I just like to have everything self containted.
I would prefer carrying a bigger case, compared to smaller case + PSU.

Carrying is a keyword for me, because the footprint argument doesnt really hold for me.
Who has a table so small that the external brick would make a difference?^^

I totally get if someone wants a small case because of looks or wanting the smallest though.
 
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JosephEK

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To me a low profile GPU might be my favorite SFF solution.
Small,
Relatively cheap,
No extra power cables,
and doesn't suffer from the RAM issues of iGPU.

The only downside is you have to probably be willing to game at 1920x1080 which isn't a problem for me honestly.

I want to get a motherboard that can use an M.2 SSD so it's one less thing I need to mount off of the motherboard and less wires to manage.

That L4 case looks great, but I'm still not sure I'm sold on the external PSU. Would the power board from my old Alienware X51 fit insite this case?
It looks something like this:
https://images-na.ssl-images-amazon.com/images/I/51zTHYeC6ML.jpg

And even if I could repurpose this old external PSU how much is this case supposed to cost? Or is that not determined yet?
 

Lone

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I don't really want to go off topic with L4 information here, but it would probably fit.
 
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DontPeek

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Oct 17, 2016
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If someone made a decent fanless SFX PSU I probably wouldn't be interested. The main draw for me is the fact that power bricks are fanless.
 

JosephEK

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Mar 6, 2017
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If someone made a decent fanless SFX PSU I probably wouldn't be interested. The main draw for me is the fact that power bricks are fanless.
Yeah I never understood how they could pull that off when it doesn't look like it can be cooled otherwise because it's completely closed in without any vents.
 

Josh | NFC

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Jun 12, 2015
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There are many good reasons for both, although more specialized products are being developed that negate some of the benefits for external bricks. I am a firm believer of using the right tool for the job.

One argument I hear all the time that I think is errant, is that an external brick takes up more volume than a normal powersupply, or at least the same volume, so why make a separate system. The problem with this is we measure chassis volume for enclosed systems, not combined part volume. When you add a square cube powersupply to a cubic chassis you aren't just adding the volume of the power supply, you are adding volume to contain the power supply proportionate to the rest of your chassis.

So for example, here is a crude diagram of a Pico Powered chassis:


The black box is the chassis, and if you had a Z height it would be easy enough to calculate the volume. The volume of the power brick ONLY adds the volume of the power brick.

Let's change our chassis to support a SFX power supply, which is a little less volume than the massive Dell 330w brick by itself:



Adding the SFX PSU didn't just add it's volume to the chassis--there now is enough room for TWO SFX units, because we don't make chassis like this:



If you want a real world example Measure the S4 MINI and add that volume to your power brick of choice. Then add up the volume of the smallest system with the same hardware loadout but with a SFX PSU and see if they come out the same.

Now of course there are neato ways of arranging hardware to reduce this effect, but I've never seen an "ultra-SFF" layout that offers the same volume efficiency as an external brick. When you add a "Pico style" or one of the G-unique combos even Flex ATX cant compete.

The bottom line is when you start to get really small, but still used standardized parts, the most efficient way to shave off liters is to separate the systems.

My tree-fiddy
 

JosephEK

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Mar 6, 2017
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So for example, here is a crude diagram of a Pico Powered chassis:

Now of course there are neato ways of arranging hardware to reduce this effect, but I've never seen an "ultra-SFF" layout that offers the same volume efficiency as an external brick. When you add a "Pico style" or one of the G-unique combos even Flex ATX cant compete.
What is "Pico"? Is it a form factor for something?
Also unsure what Flex ATX or G-unique are. I'm not used to some of these terms because up until now I've primarilly played with mATX-ATX towers.
 

Ceros_X

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Mar 8, 2016
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When I travel, my PC goes in a laptop bag. I can throw the brick in my checked lugage and not worry about baggage handlers crushing it. It would be much harder to fit my PC in a laptop bag if it was big enough to accommodate an SFX PSU, although I did eventually find a case that would work (Case with SFX PSU in laptop bag). Relocating the PSU to a brick by utilizing a PicoPSU or HDPlex 300W DC ATX allows me to fit a 3.5" HDD in there instead. Again, I could just get an external 3.5" HDD (with its own brick and cable) but there is no way I am checking that in my luggage.

Just my use case.
 
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Thehack

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What is "Pico"? Is it a form factor for something?
Also unsure what Flex ATX or G-unique are. I'm not used to some of these terms because up until now I've primarilly played with mATX-ATX towers.
Pico is a term used by mini-box for their plug in DC-DC voltage regulator board. I prefer calling it a plugin DC board or PDCB for short. G-UNIQUE is a specific line of PDCB.

Flex ATX is a standard for ATX power supply. It is a little bit smaller than SFX.