Power Supply A Guide to 12V PSU

msystems

King of Cable Management
Apr 28, 2017
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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!


Very nice. I'm surprised that such a small amount of capacitance did the trick. Maybe since you were only running a ~200w card, it doesn't take very much capacitance increase to have a big positive effect. Would need tools to really be able to measure what is going on. I tried a similar idea using 12x 470uf caps for 5,640uf on a y-splitter in parallel with the GPU 8-pin connector. And my project was copying another one which used like 16,000uf of caps.
 

BaK

King of Cable Management
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May 17, 2016
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The details and source files are available at this Github repo, so if you think this'll help you, give it a try!
Very nice!
Thanks for sharing!

Wouldn't you mind showing the whole rig of what we see in the 2nd pic?
Looks like there is lots of customized stuff!
 

patchez

Efficiency Noob
Mar 25, 2020
5
10
Of course! Happy to share; this thread helped me a lot when I built the case a few years ago.


The whole thing is 3d printed, with the exception of some 10mm threaded steel cubes I bought off of @Colinreay a few years back. The case could be made without the cubes; I just had them around already and they help the whole thing stay together nice and neat.

I printed mine on an Artillery Sidewinder X1, which has a 300mm x 300mm build plate (hence the side panels are 300mm tall). The black plastic is PLA (bad idea, it warps), with the blue being ABS. I'm hoping to design a new version over the holidays & print it in PETG the whole way through sometime next year.

It's 230mm(deep) x 162mm(wide) x 305mm(tall), for a total of ~11.3L. It's not space optimized by any means due to the ducts for the PSU and CPU cooler, but I designed it for a 12V system using the hardware I had and didn't want a riser cable.

For the 12V stuff, I have a Meanwell EPP-400-12 getting power through the switched plug on the bottom of the case, then going to my little distro board, then out to the GPU with one cable and a cheap DC/DC ATX board & the processor with the other cable. I've got a 3d printed fan holder & duct for the PSU that let it get fresh air from through the left panel. There's technically space for an SFX PSU in there, but going 12V vastly reduced the wires and made it such that there are only wires coming out of the bottom rear of the case while maintaining easy printability.
 

patchez

Efficiency Noob
Mar 25, 2020
5
10
Very nice. I'm surprised that such a small amount of capacitance did the trick. Maybe since you were only running a ~200w card, it doesn't take very much capacitance increase to have a big positive effect. Would need tools to really be able to measure what is going on. I tried a similar idea using 12x 470uf caps for 5,640uf on a y-splitter in parallel with the GPU 8-pin connector. And my project was copying another one which used like 16,000uf of caps.
My board even only has 517uF of caps; I wanted to go with only ceramics so it was limited a bit there. For my setup, it seems to be doing just as well as the bigger electrolytic I jammed in there.

My original plan was to make a 180-degree PCIe power adapter like some people use for really tall cards, but add caps to it. I ended up not doing that due to a lack of board-mount PCIe receptacles, but I'd love to see it done.

What kind of setup are you adding that much capacitance to? Must be big to need that much extra.
 

msystems

King of Cable Management
Apr 28, 2017
778
1,366
My board even only has 517uF of caps; I wanted to go with only ceramics so it was limited a bit there. For my setup, it seems to be doing just as well as the bigger electrolytic I jammed in there.

My original plan was to make a 180-degree PCIe power adapter like some people use for really tall cards, but add caps to it. I ended up not doing that due to a lack of board-mount PCIe receptacles, but I'd love to see it done.

What kind of setup are you adding that much capacitance to? Must be big to need that much extra.
I designed it,, but then I didn't have the right psu and gpu setup to really test it. Because its pretty situationally dependent. For my setup it was a solution in search of problem. But from your results, it seem promising, and with less capacitance.

 
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patchez

Efficiency Noob
Mar 25, 2020
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I designed it,, but then I didn't have the right psu and gpu setup to really test it. Because its pretty situationally dependent. For my setup it was a solution in search of problem. But from your results, it seem promising, and with less capacitance.

Very interesting! If I had found that first, I probably would've made one. I also have no idea how to test it outside of my PC (and it was sporadic on mine), but hopefully someone can make use of our work here.
 

smitty2k1

King of Cable Management
Dec 3, 2016
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I probably missed it - but what's the best way to use a Meanwell 200w PSU to power a system with a GPU that requires an external connector? (e.g. RTX 4060 LP). Right now mine is powering my low wattage CPU + GTX 1650 LP PSU, which gets it's power from the PCIe rail. Just using a regular plugin unit for the DC-ATX portion of the PSU.

I'd like to upgrade my GPU but don't want to spend the extra $$ on the HDPLEX 250w unit.
 

patchez

Efficiency Noob
Mar 25, 2020
5
10
I probably missed it - but what's the best way to use a Meanwell 200w PSU to power a system with a GPU that requires an external connector? (e.g. RTX 4060 LP). Right now mine is powering my low wattage CPU + GTX 1650 LP PSU, which gets it's power from the PCIe rail. Just using a regular plugin unit for the DC-ATX portion of the PSU.

I'd like to upgrade my GPU but don't want to spend the extra $$ on the HDPLEX 250w unit.
It might not be enough to reasonably power a 4060 as well. I'm seeing online they tend to run upwards of ~125W at full tilt on their own. Your build seems like it's relying on the CPU fan to put air over the PSU, which is almost certainly MUCH less than the 10 CFM of direct airflow the RPM-200 specs for its full 200W rating. This airflow matters a lot, and it's actually a big reason why my PSU was crapping out on me in my earlier posts in this thread. I'll post an update about that at some point. Even with a full 200W rating, I'd be a bit skeptical it's going to work with how modern GPUs have large transient power spikes.

No harm in trying, though. You (probably, don't quote me on this) won't hurt anything, it'll just crash your games / PC sometimes. If event viewer says the GPU was disconnected, it's almost certainly overloaded.

The first post in this thread has a lot of great info about connecting GPUs and using the right wires, but at this point all of the image links are dead so I'll give you a brief summary of what you'll need to do here.

Basically, you just need to get a PCIe power connector and splice the 12V and GND into your existing wiring setup. This is pretty easy overall. There are two main ways to get a PCIe power connector with wires:

1) Make one from scratch
Note that this is NOT an EPS connector for CPU power, and it is NOT what you'll find if you search for and 8-pin Mini-Fit Jr. receptacle. The keying is different. It is a Molex 455870004, which you will need along with some Mini-Fit Jr. terminals. Get the 16AWG terminals, and use 16AWG wire. You can use 18AWG wire if you want, but see if one of the reviewers has checked how much power this particular 4060 (not just any 4060) pulls from the slot vs wires. If it pulls mostly from the slot 18AWG is fine.

2) Scrap another cable
The much easier way is to take an extender, sleeved cable, 2x6pin->8pin adapter, really anything that has that PCIe power connector, and chop it. The GPU might even come with an adapter you can use. This is what I did for my build, which is a few posts above. I cut the whole thing about 2" from the connector.

After that, it's just a matter of getting it connected to the rest of your system. Use this post about PCIe power for your pinout and an explanation of why you'll end up with five GND wires, but only three 12V wires. I can't tell from your build log exactly how you run your 12V through the system, but all you need to do is connect 12V to 12V and GND to GND. Just make sure you aren't putting more power through something than it's comfortable with; I wouldn't hook it up to the HDD power connector on your PicoPSU since they say no more than 3A through it.

And always, ALWAYS check your wiring with a multimeter afterwards. I'm not responsible for any bricked parts, fires, or whatever else you manage to do.

I could give some more recommendations on that if I knew more about your setup in particular. How many 12V wires do you run throughout the system, and how big are they? Do you collect the PSU's three 12V and three GND wires right at the RPS-200, or at the PicoPSU? Wherever you do that will be the best spot to add in the GPU power wires.
 

k0n

Cable-Tie Ninja
Jul 3, 2019
205
266
what's the best way to use a Meanwell 200w PSU to power a system with a GPU that requires an external connector?
I just connected the 8 Pin directly to the 12V Meanwell. Worked flawlessly with every card except for the ARC A380 Challenger ITX which had the fans at 100% with the PC switched off, BUT this behavior is dependent on the card and might not be a problem with the RTX 4060 LP. And even if the card doesn't power down with the rest of the system... you can simply kill power (some do this always anyway).

Get an 6 to 8 Pin adapter with the colors and length you want and take the 6 Pin female of (1,49€):

 

BaK

King of Cable Management
Bronze Supporter
May 17, 2016
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Apart from the good remarks from @patchez, as @k0n said you might face the 'always on' problem depending on your GPU.
You can check how I solved it in my LiGHTPC build, using the great M2426 from Thehack.


Part list here.

But as you can see on the M2426 product page, there is still a warning asking to wait for the batch 3.
Since I would like to order more pieces of this unit, maybe @Thehack could share some light on this situation?
 

Thehack

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Mar 6, 2016
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Apart from the good remarks from @patchez, as @k0n said you might face the 'always on' problem depending on your GPU.
You can check how I solved it in my LiGHTPC build, using the great M2426 from Thehack.


Part list here.

But as you can see on the M2426 product page, there is still a warning asking to wait for the batch 3.
Since I would like to order more pieces of this unit, maybe @Thehack could share some light on this situation?
I am not sure of how the RPS-400 would react to the minor revision of batch 2. It should work as expected, as most of the issues is related to the longer rise up time of SF750.
 
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Arboreal

King of Cable Management
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Oct 11, 2015
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Thanks @BaK for that clear diagram and prompt for @Thehack about the availability of the M2426, as I would like to know what is going on with it.
I know there were component supply problems when I last asked, but it's not clear if the M2426 is actually on backorder or supply has stalled completely.
 

GuilleAcoustic

Chief Procrastination Officer
SFFn Staff
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Jun 29, 2015
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I'm trying my luck here: https://smallformfactor.net/forum/threads/lone-l5-workstation.15963/post-281799

To sum things up (cf. link above for more details), I'm considering moving to thin mini-ITX in my Lone L5 and the model I'm looking at accepts wide voltage input (12-28V).

I'd like to use a desk Meanwell AC-DC (ENP-360 in either 12V or 24V), but I'm clueless regarding what connector to use :





I know the L5 accepts Weipu SF12 connectors, so should have a 12mm cutout ... any suggestion on what to use to connect the Meanwell to the 4 pins CPU on the motherboard (accepts 12-28V) ?
 

GuilleAcoustic

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Jun 29, 2015
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Seems the board you wanted to use already has a DC jack? I just couldn't find the size. Maybe 5.1mm / 7.4mm?

View attachment 2867
It's not specified .... FSP has a matching brick, but I'm not confident running a 180W/12V with 13900T + A2000 + hungry NVMe (7450 MAX)



The thread lock DC jacks I've found are 2.0/5.5mm, 2.1/5.5mm or 2.5/5.5mm 😑 .... hence trying my luck connecting to the internal connector.

Edit: Just found that 15A / 24V series from Switchcraft : https://www.switchcraft.com/15-amp-dc-power-jacks-and-plugs/
 
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mijffs

Caliper Novice
Aug 20, 2019
28
4
hi,recently bought the meanwell epp 400 and can see from the manual where to wire in the 240 input and 12v output but the original pics of wiring are no longer available how do i switch it or will it just go live when connected to mains voltage?
 

k0n

Cable-Tie Ninja
Jul 3, 2019
205
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@mijffs mine just powered on when connected to AC.


...though now that I look at the datasheet I notice the CN95 with PS-ON function. I must have tried it without anything and it worked so I just ignored CN95.
 
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mijffs

Caliper Novice
Aug 20, 2019
28
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thanks phuncz,i will give that a go.looking at the datasheet i was thinking it might have needed a seperate 5v supply to turn on but that makes no sense as this would mean a separate 5v psu so couldnt figure it out.i guess this means it just operates like an external allways on power brick without any sense line to put it into/out of standby?
 

Thehack

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Mar 6, 2016
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thanks phuncz,i will give that a go.looking at the datasheet i was thinking it might have needed a seperate 5v supply to turn on but that makes no sense as this would mean a separate 5v psu so couldnt figure it out.i guess this means it just operates like an external allways on power brick without any sense line to put it into/out of standby?

the meanwell is always on if PS_on is not used. If PS_on is used, you would ground the PS_on pin, a LOW, is off.
 
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homeduck

Efficiency Noob
Jan 6, 2024
6
2
Hello folks, I am new here and I am having a look at this thread as I am wondering to build a similar configuration for powering my audio pc streamer (o.s. Daphile). I have bought a second hand silverstone ml09b case which hosts Sfx PSU, Hw is made up an asrock j4105 mb, 2 ssd and a slim sata drive. How can I understand which Meanwell psu fits my purpose? I mean if 100W or 150W or more.
Thank you in advance