Power Supply A Guide to 12V PSU

iy1ia

Efficiency Noob
Oct 9, 2022
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Got myself an Meanwell PSU. I intend to use it for a pure 12V build. The PSU will be wired to a PICO plug-in 24pin, a pcie 6-pin, and a CPU 4-pin. My goal is to reduce the footprint of the PSU, as well as have less cable involved. I intend the reduce the 6 18awg wires of the 6 pin into 2 16awg wires to have fewer wires. It doesn't really make sense that we still have 24pin standard when most of the regulation is done on the motherboard anyways. Here are some pics. I hope we see some more pure 12V builds in the future.



It is about 130mm x 75mm x 45 mm.


I'm waiting on the rest of my connectors before I start hooking it up.

Hello. With the recent announcement of G-Unqiue’s entry into the PICO Plug-in Type (which I will now refer to as Plug-in DC Board or PDCB for short), I have decided to revamp this thread into a general guide to Meanwell PSU. As I learn more and build into it, I will add information and update this guide as necessary so that more people can enjoy creating a 12V build.

Content Outline:

1. The benefits of 12V builds

2. Electrical safety

3. Why choose Meanwell?

4. Tools and Supplies

5. Hooking up the Meanwell PSU



---------------------------------------------------

Note* This guide is centered on the EPP 300. It has slight differences between that and the EPP100/200/400.

I. The benefits of a 12V build.

From left to right:
1. Meanwell 4x2, 200W solution; 0.20L
2. Meanwell 5x3, 400W solution; 0.37L
3. HDPlex 160W Solution, including DC-DC board in front; 0.37L Total
4. HDPlex 300W Solution, Including DC-DC Board in front; 0.55L Total
5. Flex ATX; 0.74L
6. SFX; 0.79L
*Keep in mind, non-PDCB require either custom or large bundles of wires!*

I am a huge proponent of 12V build. As SFF enthusiasts we are always looking for ways to downsize. However we must balance compatibility, efficiency, and heat. 12V is 12V. ATX systems uses 12V as the main power delivery voltage and is the main power draw of the system. It is the voltage we need the most amperage for.

However I see a lot of builds going for 16-24V wide-range inputs instead. It is up to the AC-DC PSU to create the DC power that the system will use and by using 16-24V you now must regulate the voltage again at high amperage. This is pointless and inefficient. The only benefit to using a 16-24V AC-DC PSU is that you can have a smaller internal-external barrel connector. For builders who use internal PSU, they should build with 12V in mind.

The ATX system itself is outdated, and has a lot of legacy support. At one point, motherboards were using 5V instead of the 12V as the primary voltage. However this has since changed and all modern motherboards now use 12V primarily. Yet we still have 24 pins for the motherboard. Many OEM builders have moved onto 10 pin set up to reduce components and save space.

The Plugin DC Board (PDCB) reduces cumbersome 24 wires (sometimes more depending on the PSU) to a manageable 2. A good quality 16AWG wire can carry 22 amps, that is 12*22=264W of power. Even with headroom, we can easily reduce the motherboard wires to just two.

The PDCB requires no footprint on the chassis. It plugs straight into the 24pin plug on the motherboard. Its height is not much higher than standard RAM kits. It can further output CPU 4pin and SATA power. This further reduces the amount of wires emanating from the PSU. Given a higher-specced PDCB, such as G-unique’s line of Plug&Play, it can also output 6/8pin PCIe as well. Since most 24pin plugs are fairly close to the GPU, this is also another great reduce of wires.

In conclusion, PDCB is more efficient due to requiring less voltage regulation. It is also smaller since it occupies no footprint – just the space above the 24pin motherboard plug.

II. Electrical Safety.

You are working with an open chassis that will require you to wire and possibly test unclosed.

1. Check the wire diagram once, twice, and thrice. Check all your connectors (there isn’t a whole lot so don’t be lazy) before you power on. A wrong wire will cause some frying to occur.

2. Do not touch anything when it is powered. Even the heatsinks have potential to shock you. If you are checking measurements with a multimeter, try to use the protective cap to reduce the chance of shorting.

3. Keep the test area clear of objects. Do not stand on water.

4. Use at your own risk. I prefer to test it out on my sacrifice motherboard, an AM1 + AMD Kabini.


III. Why choose Meanwell

Meanwell is easy to source, is viable, and is of reputable quality. This guide covers their EPP-line. Their specs to consider:

· 120mV pk-pk max ripple, within ATX specs​
· PFC function​
· ~92% efficiency​
· Rated for natural convection and forced convection​
· Comes in two form factors, 102mm x 51mm and 127mm x 76mm (4x2 in and 5x3 in), both take up 40mm of vertical space.​
· Single 12V output using and M3 Screw Terminal​

The following are recommended PSU, prices from Mouser USA for comparison purpose:

· EPP-100-12; $38​
o Recommended for non-gpu builds or APU builds. Max 75W natural convection, 100W force air.​

· EPP-200-12; $46​
o Recommended for low-power GPU builds. Max 140W natural convection, 200W forced air.​

· EPP-300-12; $61​
o Recommended for 6pin, 65W CPU builds. Max 200W natural convection, 300W forced air.​

· EPP-400-12; $72​
o Recommended for 8pin, 65W CPU builds. Max 250W natural convection, 400W forced air.​


IV. Tools and Supplies

Beside from your choice of PSU, you will need some parts for a Meanwell build.

· Your choice of a PDCB. I recommend from the following makers:​
o G-unique​


· 18AWG and/or 16AWG wires, 24AWG for optional wires. Any from your local hardware store will do. Get red/black if you want to color code. Be extra careful if you are only using one color like black, as you may wire it wrong.​

· You will need the correct input and output connectors. See the follow sheet:

· C14 Panel Power Entry. DIGIKEY Store **C6 for EPP 100/200 optional instead**​

· Various heatshrinks​

You will need the following tools:
(Aside from the PA-20, most generic tool will do)

· Multimeter – to confirm outputs and troubleshoot if necessary. AMAZON

· JST crimp. I recommend the PA-20 or PA-21 by Engineer (great name right?). Very high quality tool and will be useful for future builds. (Edit, the PA-21 seems superior, for this application. The PA-20 will work just fine though with some adjustments to the terminals). AMAZON

· Heatsource – Heat gun or bic lighter for heat shrinks​

· Wire stripper. AMAZON

· Philips screw driver​

· Common sense​

V. Hooking up the Meanwell PSU

There are a couple ways you can wire a 12V build. I have drawn block diagrams on how to wire them according to whether you are using a GPU or not. Remember, you can always use the high power wiring for a low power build, but not vice versa.



A. Making the C14 power entry plug. Unfortunately, I had already made it before deciding to make a guide so I don't have pictures of the process, so instead you'll have to deal with reading.

1. You will require a C14 power entry, 3x 18AWG wires of length of our choosing, the JST VHR-5N plug and 3 corresponding terminals, heat shrink, and all the listed tools.​
2. You want to strip down the length to what you need for the JST crimp. Here's a video of the crimping process. If you're not familiar, you will need extra terminals, and a sacrificial wire to practice. The regular JST crimp is pretty easy to do.​
3. Crimp 3 JST terminals and place them into pins 1, 3, 5 of the JST plug. This is fairly straightforward.​
4. Precut heat shrink "rings" to keep the bundled 3 wires together. Precut heatshrinks and place them on the wire to be shrunk over the C14 power entry prongs.​
5. WARNING, DO NOT MESS THIS PART UP: Strip the other ends of the wires, about 3/8" or 10mm, and wrap them around the prongs of the C14 power entry plug accordingly: Pin 1 is neutral, Pin 3 is Line (hot), and Pin 5 is ground. Check the diagram for orientation of the plug pins. Check, double check, and triple check. It easy to mix up black wires and if you mess up, you will burn out your PSU.​
6. Shrink the heatshrinks over the wire connected to the C14 plug, shrink the ones wrapping the 3wires so it nice and neat.​
B. Making the 6 pin PCIe Power Plug to 2 wires.
WARNING: The following requires basic knowledge in electrical wiring. Watch some videos and do lil' practice with wires if you have never attempted this. Be safe, don't leave the soldering iron unattended. Always use the holder. Shit gets hot!​
As far as I'm aware, 18 AWG wires are capable of sustaining a 75W load that is used for the 6 pin. However, for over-engineering and safety purposes, I choose to use 16 AWG on the power. This is meant to reduce the number of wires running inside your PC. You may choose to use butt connectors instead, but I wanted a cleaner appearance so I opted for solder and heatshrink. I don't exactly have a solder station or complete supplies, but my results are fairly decent. Lengths are unspecified but you should measure out the final 16 AWG to where you need it to go.​
If you are using a low power card but it still needs the 6 pin, you can use 18 AWG wire throughout. If you are using the Meanwell with 6pin power output, do not do the second combination, so you'll have a total of 4 wires.​

1. First off, you need to either buy the components required to make the 6pin power plug, or just use a donor one. You'll need 16 AWG or 18 AWG. I went with 16 AWG to be safe but specwise 18 AWG can handle the amperage.​
2. Follow the wiring diagram. Pin 2 and 5 are used for sensing and don't actually deliver power but they need to be wired anyway.​
3. Strip Pin 1,2,4,5 about 50mm from the plug. Strip pin 3 and 6 about 100mm from the plug. You'll want 10-15mm of bare wire. Do not twist the strands if you choose to solder. Add flux to the bare wire if you choose to solder.​
4. At this point you can choose to use the butt connector, or solder it. Combine them with the matching 18 AWG butt connector and crimp it. If you are soldering, align two wires on one side from the plug, and an 18AWG wire on the other side. Press them towards each other and wrap them with the solder wire. Melt the solder by heating the wire. Do heat up the wire too long as that'll start melting the insulation. See picture for example. After soldering the wire, wrap it in insulating heatshrink.​
5. Following the wire diagram, repeat this for combined 1+2 and 4+5 with pin 3 and 6. This time, use 16 AWG on the other side.​
6. On the final combined ends, you should crimp your JST connector or use a ring terminal.​
C. Wiring for Meanwell RPS-200-12/24-C. Thanks to @toddwas there is a lovely diagram for this:



First off, your guide is AWESOME. been digging though the internet to find some insight on 12v psu setups.

I got myself one of those cheap aliexpress dc-atx units (plug in dc boards) . rated for 400w, so it comes ready with 8pin pcie and the usual 4 pin cpu plug.

refering to your block diagram, is there any particular reason why you prefer to have the pcie and cpu cables running straight from the psu and not the plug in dc board?

To add context, i cant seem to boot up a z170 itx board (no POST), but it can power up an older h61 board right into win10 no issues.
 

Thehack

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First off, your guide is AWESOME. been digging though the internet to find some insight on 12v psu setups.

I got myself one of those cheap aliexpress dc-atx units (plug in dc boards) . rated for 400w, so it comes ready with 8pin pcie and the usual 4 pin cpu plug.

refering to your block diagram, is there any particular reason why you prefer to have the pcie and cpu cables running straight from the psu and not the plug in dc board?

To add context, i cant seem to boot up a z170 itx board (no POST), but it can power up an older h61 board right into win10 no issues.

this is because those plug-in boards are generally low quality and may not meet their rated specs. The meanwell PSU has standby capability, and given a way to trigger it, means it is safer to supply power directly from the meanwell.

If you don’t have a way to trigger the standby, you will have always on 12v which usually results in fans or leds being stuck on. My way around it is to use sleep instead of powering it off.

concerning weird no post issues, I don’t know why. I know some motherboards exhibits uncommon behaviors when dealing with non atx psu. Gigabyte is notorious for it and causes me all kinds of problem.
 
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iy1ia

Efficiency Noob
Oct 9, 2022
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this is because those plug-in boards are generally low quality and may not meet their rated specs. The meanwell PSU has standby capability, and given a way to trigger it, means it is safer to supply power directly from the meanwell.

If you don’t have a way to trigger the standby, you will have always on 12v which usually results in fans or leds being stuck on. My way around it is to use sleep instead of powering it off.

concerning weird no post issues, I don’t know why. I know some motherboards exhibits uncommon behaviors when dealing with non atx psu. Gigabyte is notorious for it and causes me all kinds of problem.
Thanks for the quick reply! I wish I could say my chosen PSU was a meanwell, but alas, I cheaped out on that as well and was trying my luck with an aliexpress 12v led driver. To be fair, I did my research on it and the ripple voltage was close to atx pk-pk tolerances.

Thanks for the tip on putting the pc to sleep to 'cut the power' to the fans etc.

Might tinker with the setup a little more and post my findings:

If it's any interest to you, my project's a Frankenstein of second hand parts, my maiden foray into the world of enthusiast SFF territory.

- Case : Skyreach S4 Mini
- Motherboard: Asrock superalloy Z170M-ITX/ac
- Processor: Intel i7 6700 w stock cooler
- RAM: Adata 2666mhz (2x 8gb sticks)
- Storage: 2.5in WD Blue (yes a relic from the past but I assure you it works!)
- GPU: ZOTAC GTX 1080 Mini
- Plug in Board : "450W Output Switch Power Supply Module for PC 12V DC Input 24pin DC-DC ATX Pico PSU MINI ITX PC Power Supply" link here
- PSU : "400W 12v LED power supply" link here

Plugged up the above with a standard 450w atx psu I had lying around and it works just fine. I had a gutted Alienware x51 R2 case with powerboard still inside, and that R2 powerboard (with accompanying 330w dell power brick) boots the above setup just fine as well.

Really was going for a brickless endgame though...
 
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lemmo

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Feb 17, 2017
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PSU : "400W 12v LED power supply" link here

That's an interesting option using an LED lighting AC-DC power supply to drive the 12V input to a plug-in like Pico-PSU.

Are there any GaN versions on the market now, and do you have any info on their relative efficiency and durability please?
 

Choidebu

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Aug 16, 2017
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PSU : "400W 12v LED power supply" link here
You really don't want to use LED psu. It *might* work for an apu setup, but it'll never work for >200W setup.

As soon as the pc boots that 12V is gonna derail, fast. You can see for yourself if you got a multimeter.

Just get a meanwell. EPP, RPS, even an LRS with a good +100W overhead. Sadly iirc 400W+ units aren't going to fit skyreach.
 

lemmo

Trash Compacter
Feb 17, 2017
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Thank you, and would appreciate advice on the difference between EPP, RPS and LRS types in terms of using with a PC, and also Meanwell in terms of efficiency and general quality compared to other manufacturers...
 

Thehack

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Thank you, and would appreciate advice on the difference between EPP, RPS and LRS types in terms of using with a PC, and also Meanwell in terms of efficiency and general quality compared to other manufacturers...
EPP and RPS are the same as far as I can see. Just one more stringent for medical use I think. Efficiency is around gold rated.

Meanwell is the ol’ reliable in terms of PSU for industrial application. Not the most power dense but reasonable price and good reliability. You will see them noted as a feature for machines, like 3D printers instead of some no name PSU.
 

BaK

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You really don't want to use LED psu. It *might* work for an apu setup, but it'll never work for >200W setup.
LED PSU was a no go for @infoberg's APU build:
 
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Valantar

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Jan 20, 2018
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PSU : "400W 12v LED power supply" link here
Just the fact that the 400W unit is listed with a net weight of 250g makes me think this would qualify for JonnyGuru's coveted Gutless Wonder award. Not that weight is a direct indication of much, but very low weight and very low price is a tell-tale sign of an overspecced, underbuilt unit. I'd be shocked if that thing could handle 400W output for any amount of time without failing, either quietly or explosively. There's just no way of fitting the required componentry and heat sinking into that low a weight for reliable, stable 12V400W output. The narrow input voltage range also speaks to an old and/or basic design, and it likely lacks active PFC. It's also likely quite inefficient, which will further accelerate its failure unless carefully cooled.

MW aren't cheap, but they're very efficient, deliver their rated power very stably, and are extremely reliable. (And compared to many other industrial PSU makers they are quite affordable.) If at all possible, I would go that route. It's entirely possible that your boot failures are due to out-of-spec voltages either due to poorly calibrated outputs or excessive voltage droop at boot as the load turns on. Different boards have different tolerances, and in my experience newer systems are typically more sensitive as they're pushed harder in terms of clocks. It might also be down to excessive ripple, though then you'd likely be able to hear the VRMs of the working system fighting to suppress that when it's running too.
 

Curiosity

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To expand on that-
I don't think I'd be willing to use any PSU off Ali I can't find a datasheet for in a PC unless it's for a very cheap low end build
 

iy1ia

Efficiency Noob
Oct 9, 2022
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Thanks all for your inputs! Sorry I couldn't reply sooner. Indeed this is more of an experiment of what is possible. Still learning a ton from quality contributors such as yourselves.

That said, I do have one last try on the current set-up, and that is to try and underclock and undervolt to see if it starts up. Chanced upon another builder with very similar situation here: https://silentpcreview.com/forums/viewtopic.php?t=61784

Apologies if my approach seems rather haphazard as I've skipped documenting a fair deal of my intermediate steps in troubleshooting.

I'll update nonetheless on my success or lack thereof in getting the system to POST.
 

iy1ia

Efficiency Noob
Oct 9, 2022
6
1
Thanks all for your inputs! Sorry I couldn't reply sooner. Indeed this is more of an experiment of what is possible. Still learning a ton from quality contributors such as yourselves.

That said, I do have one last try on the current set-up, and that is to try and underclock and undervolt to see if it starts up. Chanced upon another builder with very similar situation here: https://silentpcreview.com/forums/viewtopic.php?t=61784

Apologies if my approach seems rather haphazard as I've skipped documenting a fair deal of my intermediate steps in troubleshooting.

I'll update nonetheless on my success or lack thereof in getting the system to POST.
Forgot to add an important update. I have since gotten my hands on a mean well LRS-350-12.

Hooked it up in place of the cheaper LED driver, but the outcome is still the same.

In other words, the motherboard still does not POST. Hence the next step of undervolting and underclocking
 

BaK

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Forgot to add an important update. I have since gotten my hands on a mean well LRS-350-12.

Hooked it up in place of the cheaper LED driver, but the outcome is still the same.
Did you try powering up your system without the 1080 mini, as a first check?
 

xredlinexx1

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Mar 18, 2019
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hey guys, is it feasible to use a Meanwell 500w as an external brick, then once inside the case the cable splits in parallel? One cable going to a pico psu attached to the motherboard, and the other going directly to a GPU?

Both pico psus and GPUs take 12V, right?

I'm interested in basically removing nearly all the psu out of the case (Sparrow MQ5), in order to make room for either a longer gpu or adding a radiator for water cooling.
 

msystems

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Apr 28, 2017
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hey guys, is it feasible to use a Meanwell 500w as an external brick, then once inside the case the cable splits in parallel? One cable going to a pico psu attached to the motherboard, and the other going directly to a GPU?

Both pico psus and GPUs take 12V, right?

I'm interested in basically removing nearly all the psu out of the case (Sparrow MQ5), in order to make room for either a longer gpu or adding a radiator for water cooling.
Yes, this is essentially what g unique does and jhack m2426. Compared to ATX, You save a lot of space, at the expense of needing some customized wiring.

When you buy your pico make sure its one designed for 12v and not 19v as there are both types.

The 12v variants just "pass through" the 12v and don't have to step it down
 
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robbee

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I wouldn't use a Meanwell externally though, it is just too dangerous having a non insulated high voltage converter in such an exposed location. High voltage cables and devices require at least double insulation, that's why regular bricks are made in plastic and completely sealed.
 
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xredlinexx1

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Mar 18, 2019
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I wouldn't use a Meanwell externally though, it is just too dangerous having a non insulated high voltage converter in such an exposed location. High voltage cables and devices require at least double insulation, that's why regular bricks are made in plastic and completely sealed.
That is a great point. I was planning to 3d print an enclosure, but it might not be able to handle the temperatures.

I suppose i could go with something like this: https://www.mouser.com/ProductDetail/MEAN-WELL/GST360A12-C8P?qs=rSMjJ%2B1ewcQsFVFxjhSAPg==

It actually uses molex, so it might be easier to put together.
 

xredlinexx1

Average Stuffer
Mar 18, 2019
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Are there any off the shelf parts for wiring up a 330w DC brick to a gpu and pico psu? or would it mostly have to be diy?

there are bricks with 6 pin molex output. maybe some psu molex y splitters could work?
 

patchez

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Mar 25, 2020
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Hey all,

Just wanted to chip in with my 12V experience in case it helps someone else. A few months ago, I upgraded my system (R5 1600, GTX 970, EPP-400-12), to a 3060ti. I started having several GPU issues with game and Windows crashes, most of which had some version of "GPU Not There Anymore" as the error.

I remembered people talking about instantaneous current draw on 30 series GPUs when they came out, so I figured the EPP-400 just didn't have enough output capacitance to keep it going during spikes. To fix this, I wedged a 1000uF capacitor in the EPP-400's output terminals. And it actually solved it! No more crashes.

In an effort to reduce jank, I designed a circuit board that has a bunch of capacitors on it, and two XT30s for 12V outputs. I'm aware that XT30s are only rated for 15A (180W at 12V) continuous, but my 3060ti only pulls 200W, and I'm willing to risk it for how small this solution is. It screws directly onto the EPP-400's terminals using the included screws, so mounting is pretty easy and it helps with wiring anyways.

The details and source files are available at this Github repo, so if you think this'll help you, give it a try!