A Guide to 12V PSU

Thehack

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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 Mini-Box
o Pico-Box
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:



 
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Aibohphobia

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Ripple is 120mV max which is the max for the ATX spec. Hopefully average ripple is under that so you don't have issues but if you run into stability problems that's probably the reason.
 
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Thehack

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Aibohphobia

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Ah, I missed that. And wow, I so wish we got these kind of test reports for consumer power supplies from the manufacturer.
 

confusis

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Not much bigger than the HDPlex AC-DC.. Interesting!
 

Thehack

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Not much bigger than the HDPlex AC-DC.. Interesting!
Yup. Combine that with a Pico PSU you can have a very small build.

Also, I wonder about the viability of building a chassis of it as an external PSU, plugging into the chassis via a 4pin Mini Fit and power a pure 12V system. This allows you to return even more powerful things inside something an S4 mini. I'm sure @Aibohphobia can concoct something for us if it proves viable!
 

Kmpkt

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You could also use the 24V variant of this unit with the new HDplex units I believe as they are 16-24V DC Input. I'm just thinking this could be a better solution as the pinout and rated wattage of the new DC Plugless should be higher than that of the 12V Pico solution.
 
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Thehack

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You could also use the 24V variant of this unit with the new HDplex units I believe as they are 16-24V DC Input. I'm just thinking this could be a better solution as the pinout and rated wattage of the new DC Plugless should be higher than that of the 12V Pico solution.
Yes that is true. However, I find that the HDPlex adds more complexity to the situation. The PSU is already regulating the voltage, why add another board and more wires? Wires take up more space than we give it credit for. If we are using an AC-DC PSU, might as well have a pure 12V system.


The new 160W plugin should be very useful and can remove even more wires. For my use, I will be using the less expensive 160W plugin from Pico-Box, rated for 8A on the 12V. I will not use the 4 pin CPU from the Pico-box but I will add one directly from the Meanwell PSU, so that it won't exceed the rating on the plug-in. I suspect that the issue with such a low rating is that either the traces aren't fat enough, or the 18awg wires can't handle high current, or the p4 connector isn't high enough gauge (it looks like 22 awg to me). It is a simple pass-through voltage system, so it just requires beefier connectors and traces to handle higher wattage.
 
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Thehack

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Got it running. Outputs at a sweet 12.08V according to my Amazon multimeter.

Next stage:

Load test with 750ti. Then I will load test with 1060 3GB + this mobo. Once it passes all of that, I'll load test it with my i5 + 6500 in the case.

 
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Ceros_X

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Nice! Missed the guide because of the stealth edits. Good stuff!

Edit: I think some pictures would be extremely helpful. In particular, pictures of the connectors and whatnot in Tools in supplies. I could stop and Google each item while reading but a product picture (maybe with a link to where we could purchase/where you recommend we purchase) make me not have to open a new tab etc (especially annoying on a phone).

Eventually it'd be cool to do picture size comparisons between a FlexAtx, Meanwell, SFX.

Maybe shots of the PDCBs in the beginning for newbies.

Thanks for all the info so far!
 
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Thehack

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Nice! Missed the guide because of the stealth edits. Good stuff!

Edit: I think some pictures would be extremely helpful. In particular, pictures of the connectors and whatnot in Tools in supplies. I could stop and Google each item while reading but a product picture (maybe with a link to where we could purchase/where you recommend we purchase) make me not have to open a new tab etc (especially annoying on a phone).

Eventually it'd be cool to do picture size comparisons between a FlexAtx, Meanwell, SFX.

Maybe shots of the PDCBs in the beginning for newbies.

Thanks for all the info so far!
Good ideas. I'll add in pictures and more info as I get time.
 

ricochet

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It'd need ventilation so that means holes in the casing that idiots can stick things in and electrocute themselves. So I wouldn't touch that kind of project with a 10 foot (3.05m) pole :p
Concur, I would blow my skin off in a heart beat! But very interesting idea for those who know what they are doing and for suitable cases. Though HDPLEX has a few more wires it is still less than SFX and FlexATX and much safer!
 
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Ceros_X

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Thank you for adding links and pics!

It doesn't seem like there is a huge size advantage over the HDPLEX300W AC-DC though. Also, what are the two objects out front in the size comparison?
 
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Thehack

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Thank you for adding links and pics!

It doesn't seem like there is a huge size advantage over the HDPLEX300W AC-DC though. Also, what are the two objects out front in the size comparison?
Yup. There were good suggestions so I'm implementing some. Let me know if you have more questions, this is a guide meant for newbies so I want to cover everything.

The objects in front are the DC-DC board. The HD-PLEX 300W AC-DC and DC-DC combo takes up 0.55L, not including cables. The Meanwell 400W takes up .37L total. Including cables, the HD-PLEX is almost twice the size of the meanwell in volume. However, it is split into two parts, so it may benefit certain layouts more, but for a 300-400W build, the Meanwell is easily more space efficient.

With the new 16-24V PDCB from HD-PLEX, HD-PLEX becomes a lil' bit more competitive in the 200W range in terms of space efficiency. However, it is as not cost effective. The PDCB is going to be $35-40. With a Meanwell, I can use a cheaper Pico-BOX PDCB, and just use the 12V from the PSU to supply the rest of the system power. Though if you don't have tools or time, then I see that the HD-PLEX and their PDCB is a better combo.
 
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Thehack

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Another update. Success on the GPU powered by the meanwell 12V. Initially the GPU wouldn't boot unless I wired all the PCIe 6 pin wires. I was trying to get away with 4 wires, as the spec only requires 4, 1 is sense, and 1 is optional. Whatever the case, I got 6 wires into the PSU and it ran the "torture" test just fine. Obviously CPU bottlenecked. I'm waiting on my G-Unique PSU and my already just put in an order for my case. It'll be a month until I can complete the build. I'll try to have this guide fleshed out by then. I'm adding it in here and there.


 

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I appreciate your work on this. I think one of these could be an ideal fit for my case also. Do you have a way to measure the temperature, or just comment in general terms?
 
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CC Ricers

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Thanks to your recommendations I'm going to buy the EPP-200 instead of HDPLEX internal 160W unit. It's smaller plus it will allow me to use the C7/C8 connection as no earth connector is required.

You might want to add in the OP that for CPU/APU only setups you can go for the 200W version and mention C14 isn't necessary, despite the block diagram you have. So you can just use a C8 2-prong plug. It would be silly to have that big 3-prong plug in a case only made for a ITX board :D

I will actually try to use the 200W version with a 6-pin GPU, the GTX 1060. Couple it with a 35W CPU to keep power consumption low. The DC-DC unit will be a 160W HDPLEX with a custom wire harness, where I modded the 8-pin CPU cable to split it into a 4-pin CPU and a 6-pin GPU. I have actually used a 6-pin GPU (GTX 950) with this custom mod and a 200W power brick before, and it ran well.
 

Thehack

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Thanks to your recommendations I'm going to buy the EPP-200 instead of HDPLEX internal 160W unit. It's smaller plus it will allow me to use the C7/C8 connection as no earth connector is required.

You might want to add in the OP that for CPU/APU only setups you can go for the 200W version and mention C14 isn't necessary, despite the block diagram you have. So you can just use a C8 2-prong plug. It would be silly to have that big 3-prong plug in a case only made for a ITX board :D

I will actually try to use the 200W version with a 6-pin GPU, the GTX 1060. Couple it with a 35W CPU to keep power consumption low. The DC-DC unit will be a 160W HDPLEX with a custom wire harness, where I modded the 8-pin CPU cable to split it into a 4-pin CPU and a 6-pin GPU. I have actually used a 6-pin GPU (GTX 950) with this custom mod and a 200W power brick before, and it ran well.
Good luck! It is rated for airflow so hopefully as long as you have some kind of airflow around it you should be okay. But the road ahead is paved with unknowns and it is our job to clear the path for others to follow.

I'll update that info you suggested.