Splitting 400w DC Input?

xredlinexx1

Average Stuffer
Original poster
Mar 18, 2019
65
11
Hi,

Say you have an external 400w ac/dc hdplex providing dc power to your computer. Could you split the 400w dc input, using molex cables, into two 200 watt inputs. I'm wondering if this could be done to have 1 200w dc input directly power a GPU and another power an hdplex 200w direct-plug?
 

xredlinexx1

Average Stuffer
Original poster
Mar 18, 2019
65
11
You can split any way you want as long as the total load doesn't exceed 400W.
That's what I figured, but I'm surprised I've never seen anyone do it. Seems like a great way to reduce wires and components. It does seem difficult/impossible to find existing molex adapters to achieve this though. Maybe custom cables would have to be made
 

ExplodingWaffle101

SFF Lingo Aficionado
May 11, 2018
129
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That's what I figured, but I'm surprised I've never seen anyone do it. Seems like a great way to reduce wires and components. It does seem difficult/impossible to find existing molex adapters to achieve this though. Maybe custom cables would have to be made
+
woah, hold on! I think @Kilrah forgot to mention that HDPlex AC/DCs output 19v while your computer bits run at 12v (which is what the 200W DC/DC converts it down into). plugging 19v into a gpu would almost certainly fry it.
 

xredlinexx1

Average Stuffer
Original poster
Mar 18, 2019
65
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What about splitting to two hdplex 200w? One would be a dummy one that just connects the pcie connector to the GPU and the other powering the Mobo.
 

lambino

Chassis Packer
Jul 19, 2019
17
8
What about splitting to two hdplex 200w? One would be a dummy one that just connects the pcie connector to the GPU and the other powering the Mobo.


This is what you need. Even with a meanwell RPS/EPP 400W 12V, the ripple is a little too high to recommend plugging directly into your GPU 12V inputs, it's not clean power (ATX Spec is 120mV max ripple for the 12V line, meanwells are something like 200mV).

Some people have done it that way anyway though, connecting a meanwell straight to the GPU, including TheHack and another guy around here using "Dual PSUs". Up to you.

In your shoes, I would buy a Meanwell RPS 500 12V and the One2 distro Board+the bundled Pico PSU. Why 500W instead of 400W? Higher fanless wattage rating, 320W on the 500W Meanwell vs 280W on the 400W Meanwell.

If you're a real baller you might consider buying this brand new 600W AC-DC unit instead of the Meanwell. It's rater at 600W with a fan and the full 400W fanless! Only issue is that its much more expensive and difficult to find since it was literally just released.
 

smitty2k1

King of Cable Management
Dec 3, 2016
917
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This is what you need. Even with a meanwell RPS/EPP 400W 12V, the ripple is a little too high to recommend plugging directly into your GPU 12V inputs, it's not clean power (ATX Spec is 120mV max ripple for the 12V line, meanwells are something like 200mV).

Some people have done it that way anyway though, connecting a meanwell straight to the GPU, including TheHack and another guy around here using "Dual PSUs". Up to you.

In your shoes, I would buy a Meanwell RPS 500 12V and the One2 distro Board+the bundled Pico PSU. Why 500W instead of 400W? Higher fanless wattage rating, 320W on the 500W Meanwell vs 280W on the 400W Meanwell.

If you're a real baller you might consider buying this brand new 600W AC-DC unit instead of the Meanwell. It's rater at 600W with a fan and the full 400W fanless! Only issue is that its much more expensive and difficult to find since it was literally just released.

I'm still plotting a Meanwell 400w/500w+J-Hack Distro in a mini-sandwich case one of these days when I have money.
 

xredlinexx1

Average Stuffer
Original poster
Mar 18, 2019
65
11
This is what you need. Even with a meanwell RPS/EPP 400W 12V, the ripple is a little too high to recommend plugging directly into your GPU 12V inputs, it's not clean power (ATX Spec is 120mV max ripple for the 12V line, meanwells are something like 200mV).

Some people have done it that way anyway though, connecting a meanwell straight to the GPU, including TheHack and another guy around here using "Dual PSUs". Up to you.

In your shoes, I would buy a Meanwell RPS 500 12V and the One2 distro Board+the bundled Pico PSU. Why 500W instead of 400W? Higher fanless wattage rating, 320W on the 500W Meanwell vs 280W on the 400W Meanwell.

If you're a real baller you might consider buying this brand new 600W AC-DC unit instead of the Meanwell. It's rater at 600W with a fan and the full 400W fanless! Only issue is that its much more expensive and difficult to find since it was literally just released.

Thank you for the informative reply! Are the meanwell units safe to have outside the case and behind a desk, similar to a power brick?
 

lambino

Chassis Packer
Jul 19, 2019
17
8
The MeanWell units come with a variety of enclosure options, I'd say anything but the bare pcb version is safe enough to have outside your pc case, as long as it's away from water and other conductors. I actually have mine just sitting on my desk (the closed mesh version RPS 500W 24V) powering an HDPlex 400W DC-ATX. Keep in mind that if you want to push your Meanwell to its max wattage, you need to actively cool it, so grab a model with a side mount or top mount for a fan, or get the mesh model and fabricate a way to attach a fan to it. I run mine fanless just fine, but i dont game.

Let me know if you really decide to buy the Meanwell, you'll need to pick up some special connectors and even a crimper to plug in to it.
 
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xredlinexx1

Average Stuffer
Original poster
Mar 18, 2019
65
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The MeanWell units come with a variety of enclosure options, I'd say anything but the bare pcb version is safe enough to have outside your pc case, as long as it's away from water and other conductors. I actually have mine just sitting on my desk (the closed mesh version RPS 500W 24V) powering an HDPlex 400W DC-ATX. Keep in mind that if you want to push your Meanwell to its max wattage, you need to actively cool it, so grab a model with a side mount or top mount for a fan, or get the mesh model and fabricate a way to attach a fan to it. I run mine fanless just fine, but i dont game.

Let me know if you really decide to buy the Meanwell, you'll need to pick up some special connectors and even a crimper to plug in to it.
Cool, thanks! i might go down this route. Do you know of any full enclosures, heatsinks, or ones that could be 3d printed for the Meanwell 500w? It seems fairly unsafe and unaesthetic with parts of the board exposed. I have some experience with soldering and electric circuits, so this would be a fun project.
 

lambino

Chassis Packer
Jul 19, 2019
17
8
Cool, thanks! i might go down this route. Do you know of any full enclosures, heatsinks, or ones that could be 3d printed for the Meanwell 500w? It seems fairly unsafe and unaesthetic with parts of the board exposed. I have some experience with soldering and electric circuits, so this would be a fun project.


This box would fit it like a glove, you'd just have to cut into it for fans, I/O, and mounting (adding rubber grommets where appropriate to protect cables, check McMasterCarr.com). That's how I would do it.
 

james1976

Chassis Packer
Mar 9, 2021
15
1
what all would
This box would fit it like a glove, you'd just have to cut into it for fans, I/O, and mounting (adding rubber grommets where appropriate to protect cables, check McMasterCarr.com). That's how I would do it.
i need with a meanwell psu to power both a 400 and 200 watt hd plex ? i was looking at this unit here Amazon product i don't really know if it is good or not i been looking for a week also on the hdplex 200 there are 2 pins 5v sync and on the 400 above 24 pin there are 4 jumper pins ps on and pwr ok what are they used for ? the power input on the hd plex psus are same as 6pin pcie so could i use some long pcie extension i got to got to from the psu to the hdplex units ?
 

REVOCCASES

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REVOCCASES
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Apr 2, 2020
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Do you know of any full enclosures, heatsinks, or ones that could be 3d printed for the Meanwell 500w?

I made a custom aluminum case for RPS / EPP series Meanwell PSUs some time ago. You just need to put the PSU and a fan inside. I have a few left if you need one.
 
Last edited:

jakejm79

Average Stuffer
Mar 22, 2021
62
52
This is what you need. Even with a meanwell RPS/EPP 400W 12V, the ripple is a little too high to recommend plugging directly into your GPU 12V inputs, it's not clean power (ATX Spec is 120mV max ripple for the 12V line, meanwells are something like 200mV).

Some people have done it that way anyway though, connecting a meanwell straight to the GPU, including TheHack and another guy around here using "Dual PSUs". Up to you.

In your shoes, I would buy a Meanwell RPS 500 12V and the One2 distro Board+the bundled Pico PSU. Why 500W instead of 400W? Higher fanless wattage rating, 320W on the 500W Meanwell vs 280W on the 400W Meanwell.

If you're a real baller you might consider buying this brand new 600W AC-DC unit instead of the Meanwell. It's rater at 600W with a fan and the full 400W fanless! Only issue is that its much more expensive and difficult to find since it was literally just released.
You have your information backwards:
The Meanwell RPS line of power supplies are within ATX spec for ripple/noise (RPS-400-20201020.cdr (meanwell.com)) shows 120mV for 12V model, which is 1% and within ATX spec and the EEP line is actually lower at 100mV for the 12V variant (EPP-200-20201020.cdr (meanwell.com)).

Meanwhile that 'baller' PSU you suggested using actually has 240mV for 12V so 2% and well outside ATX spec (CUS600M Series Datasheet (mouser.com)).


The OP should do the exact opposite of your suggestion.
 
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