Power Supply A Guide to 12V PSU

ermac318

King of Cable Management
Mar 10, 2019
650
502
You can only do a direct ac-dc to motherboard if your motherboard supports 12V in.

100% of it needs to go into the Picopsu.
@Thehack is right, I went back and forth with him about a year ago on using the DA-2 in this way. You will need to find a board that accepts 12v input directly. Take a look at server/workstation boards like those from AsRockRack or SuperMicro and you may find ones that would support this. @fabio did a similar build with a Meanwell 12V PSU and the ASrock Rack C246 WSI motherboard.
 

Valantar

Shrink Way Wielder
Jan 20, 2018
1,621
1,481
I hope this is on topic: my battle plan is to use a Dell DA-2 and this https://www.newegg.com/p/N82E16812198032 PCIe to 4+4 pin feeding one 4 pin into a PicoPSU the other into the motherboard. The only possible problem I can see with this solution is the motherboard would receive 12V before the ATX part comes on. Can that be a problem?

According to https://egpu.io/forums/psu-cables/us3-dell-da-2-pcie-splitter/ it's possible to force a PCIe 6 pin like this on the DA-2 and then use a highly sophisticated McGyver device to force the DA-2 to be on :) And yes, I have a multimeter and I will test the voltages before feeding them anywhere.
Doesn't your PicoPSU provide a 4-pin EPS connector? Use that, don't connect it directly from the power brick.
 

REVOCCASES

SFF Guru
Bronze Supporter
Apr 2, 2020
1,103
989
www.revoccases.com
I hope this is on topic: my battle plan is to use a Dell DA-2 and this https://www.newegg.com/p/N82E16812198032 PCIe to 4+4 pin feeding one 4 pin into a PicoPSU the other into the motherboard. The only possible problem I can see with this solution is the motherboard would receive 12V before the ATX part comes on. Can that be a problem?

According to https://egpu.io/forums/psu-cables/us3-dell-da-2-pcie-splitter/ it's possible to force a PCIe 6 pin like this on the DA-2 and then use a highly sophisticated McGyver device to force the DA-2 to be on :) And yes, I have a multimeter and I will test the voltages before feeding them anywhere.

I'm pretty excited about the idea. If we could make it work this would mean we could use any cheap pico-psu and just need a good and powerful 12VDC power supply to provide enough juice to CPU and GPU.

I might have found the McGyver device we need:


Put this between the 12V line for CPU / GPU and connect the trigger signal input to the MOBO front header 5V pin. When the pico-psu starts up the PC, the McGyver device is activated by the 5V (high level trigger) coming from the MOBO and lets the juice flow to CPU / GPU

(In theory)
 

chx

Master of Cramming
Silver Supporter
May 18, 2016
544
276
Doesn't your PicoPSU provide a 4-pin EPS connector? Use that, don't connect it directly from the power brick.

OK, OK, apparently bad idea. But doesn't all 8 pins need to be connected? The PicoPSU only has a single 4 pin :/ that's why I wanted to do this. Too bad if it doesn't work :/



Put this between the 12V line for CPU / GPU and connect the trigger signal input to the MOBO front header 5V pin. When the pico-psu starts up the PC, the McGyver device is activated by the 5V (high level trigger) coming from the MOBO and lets the juice flow to CPU / GPU

Well, you can't switch the Dell adapter with this on, that still need to be On all the time to allow for the PicoPSU to start but yes , I could put this in line with the problematic 4 pin -- I guess it switches fast enough it's not really a problem the second block of 12V coming online just a little bit later? I would still need a pinout for the three pin header to be able to do this. Connecting the MOSFET to the PicoPSU is easy: https://www.moddiy.com/products/Mini-PC-Mini-2-Pin-to-SATA-Power-Cable.html I just need to know which leg is the signal wire...
 

Valantar

Shrink Way Wielder
Jan 20, 2018
1,621
1,481
OK, OK, apparently bad idea. But doesn't all 8 pins need to be connected? The PicoPSU only has a single 4 pin :/ that's why I wanted to do this. Too bad if it doesn't work :/
No, most CPUs run perfectly fine with just 4 pins. 8 are only necessary for very power hungry ones, and even then typically only when overclocking.
 

Thehack

Spatial Philosopher
Original poster
Creator
Bronze Supporter
Mar 6, 2016
2,722
3,477
J-hackcompany.com
I'm pretty excited about the idea. If we could make it work this would mean we could use any cheap pico-psu and just need a good and powerful 12VDC power supply to provide enough juice to CPU and GPU.

I might have found the McGyver device we need:


Put this between the 12V line for CPU / GPU and connect the trigger signal input to the MOBO front header 5V pin. When the pico-psu starts up the PC, the McGyver device is activated by the 5V (high level trigger) coming from the MOBO and lets the juice flow to CPU / GPU

(In theory)

Can't do this. It needs to be logic. If it is not logic based, it'll latch high when you try to turn it off.

I did design the Distro 400 for this purpose, with a logic based triggrr, but it is generally unpopular.
 

REVOCCASES

SFF Guru
Bronze Supporter
Apr 2, 2020
1,103
989
www.revoccases.com
Yeah not sure if it would work. But they said in the description it works logic.
  • Logic Operating Voltage: 3.3~10V DC
  • Logic Control Signal: 3.3~10V DC
For your Distro you are using Mosfets together with a logic IC to switch the 12V rail, right? How about the caps and inductor? Are they only for filtering or...? If the board could be designed a bit smaller maybe it would be more popular?

Don't you think it's possible to do something similar like this:


If we wouldn't need the inductor and caps the load switch board could be designed pretty cheap and small.
 
Last edited:

REVOCCASES

SFF Guru
Bronze Supporter
Apr 2, 2020
1,103
989
www.revoccases.com
OK, OK, apparently bad idea. But doesn't all 8 pins need to be connected? The PicoPSU only has a single 4 pin :/ that's why I wanted to do this. Too bad if it doesn't work :/





Well, you can't switch the Dell adapter with this on, that still need to be On all the time to allow for the PicoPSU to start but yes , I could put this in line with the problematic 4 pin -- I guess it switches fast enough it's not really a problem the second block of 12V coming online just a little bit later? I would still need a pinout for the three pin header to be able to do this. Connecting the MOSFET to the PicoPSU is easy: https://www.moddiy.com/products/Mini-PC-Mini-2-Pin-to-SATA-Power-Cable.html I just need to know which leg is the signal wire...

True, the DA2 would have to be always "ON" . But despite having slightly higher power consumption when the PC is turned off that shouldn't be an issue.

Guess I'll just order one and see how it works. ;)
 

Thehack

Spatial Philosopher
Original poster
Creator
Bronze Supporter
Mar 6, 2016
2,722
3,477
J-hackcompany.com
True, the DA2 would have to be always "ON" . But despite having slightly higher power consumption when the PC is turned off that shouldn't be an issue.

Guess I'll just order one and see how it works. ;)

It's an issue because the fan sometimes stay on or the LED does as well.
 

Thehack

Spatial Philosopher
Original poster
Creator
Bronze Supporter
Mar 6, 2016
2,722
3,477
J-hackcompany.com
Yeah not sure if it would work. But they said in the description it works logic.
  • Logic Operating Voltage: 3.3~10V DC
  • Logic Control Signal: 3.3~10V DC
For your Distro you are using Mosfets together with a logic IC to switch the 12V rail, right? How about the caps and inductor? Are they only for filtering or...? If the board could be designed a bit smaller maybe it would be more popular?

Don't you think it's possible to do something similar like this:


If we wouldn't need the inductor and caps the load switch board could be designed pretty cheap and small.

If you plug the trigger into a 5v header, the header is not a logic signal. It is a power rail, hence you may get weird issues.


Size isn't really a problem. The problem is that external is pretty much dead, and there is no internal 12v ACDC that fits popular products.
 

REVOCCASES

SFF Guru
Bronze Supporter
Apr 2, 2020
1,103
989
www.revoccases.com
It's an issue because the fan sometimes stay on or the LED does as well.

We want to use a normal low wattage PICO together with the DA2. So the PICO will turn OFF everything except 5VSB. Why would this cause issues? It's basically the same like HDPLEX 200 setup which also does not turn off the AC-DC part. Only issue is to find a way to turn OFF/ON the additional 12V for GPU/CPU together with the rest.

Like you said, similar like the DISTRO400.
 

REVOCCASES

SFF Guru
Bronze Supporter
Apr 2, 2020
1,103
989
www.revoccases.com
Size isn't really a problem. The problem is that external is pretty much dead, and there is no internal 12v ACDC that fits popular products.

True, the MEANWELL 400/500 fits in some cases which support FLEX but not in all. It's a bit bigger. But this can be changed using a custom case for these PSUs.

PS: I have recommended your DISTRO400 to some of my customers but they wouldn't get one because:

A) they didn't understand the concept
B) they didn't know where to put it
C) they were looking for something cheaper

Gury actually had a nice idea combining a tiny FLEX-mountable AC-DC with his Archdemon Plugins as a ready to use package but it's not exactly cheap.
 

Thehack

Spatial Philosopher
Original poster
Creator
Bronze Supporter
Mar 6, 2016
2,722
3,477
J-hackcompany.com
True, the MEANWELL 400/500 fits in some cases which support FLEX but not in all. It's a bit bigger. But this can be changed using a custom case for these PSUs.

PS: I have recommended your DISTRO400 to some of my customers but they wouldn't get one because:

A) they didn't understand the concept
B) they didn't know where to put it
C) they were looking for something cheaper

Gury actually had a nice idea combining a tiny FLEX-mountable AC-DC with his Archdemon Plugins as a ready to use package but it's not exactly cheap.

The Meanwell is good for certain reasons, but a properly available Enhance 600W FlexATX will just kill it. You wouldn't have to worry about power entry, having a case, dealing with screw terminals. A proper flexatx psu is just a better end-user product in many ways.
 

REVOCCASES

SFF Guru
Bronze Supporter
Apr 2, 2020
1,103
989
www.revoccases.com
connect the trigger signal input to the MOBO front header 5V pin

was just going to try my idea with some components I had laying around... well only the NUC has that PIN I wanted to use but ITX boards don't. So it doesn't work the way I was thinking.

The Meanwell is good for certain reasons, but a properly available Enhance 600W FlexATX will just kill it. You wouldn't have to worry about power entry, having a case, dealing with screw terminals. A proper flexatx psu is just a better end-user product in many ways.

As internal solution absolutely. Problem is the availability of good (and silent) FLEX PSUs.

How about your new project, the update DISTRO with wide voltage input? What would be the use case scenario / advantage? Wouldn't you have the same problem that FLEX or HDPLEX 400 is the overall easier solution for the customer?
 

REVOCCASES

SFF Guru
Bronze Supporter
Apr 2, 2020
1,103
989
www.revoccases.com
A bit off-topic, but how did you come to that conclusion? Looking at the popularity of cases like the S4 mini and L5, I'd hardly call it dead...

Second that. The only reason why I started to look into the 12V / Pico-Psu world is because customers asked me if I had an external power solution or at least something to make up space in their enclosures for their mods.
 

Thehack

Spatial Philosopher
Original poster
Creator
Bronze Supporter
Mar 6, 2016
2,722
3,477
J-hackcompany.com
A bit off-topic, but how did you come to that conclusion? Looking at the popularity of cases like the S4 mini and L5, I'd hardly call it dead...

The S4M is actually the prime example of my point. The S4M is pretty much an exclusive internal build (see each build log). My solution was designed for the S4M pretty much, but after the 400W hdplex ac-dc came out, it's been 99% internal builds.

L5 is for 200W build, which bricks aren't as bulky and excessive in size. But there is also a lot of pressure there for an internal unit. If there was an easily available one, it'll kill external overnight
 
  • Like
Reactions: robbee

Advokatrix

Trash Compacter
Dec 29, 2017
50
32
As it seems, the external pico psu (adaptec) likes to fail?! I try to power an i5-8400 + GTX 1650s + M.2 + 2x8GB RAM modules. Even at 70% power target and -100 on the core clock on my 1650s, my whole system suddenly shuts down at around 137-145w total system power draw.

Honestly, I run my 6pin via molex on the "accessories connector" which is not ideal and I could try soldering the 6pin directly to the power inlet, just to releave the pico 160xt. But is there a chance that it could work out?
I really want it to work and dont wanna by a second adaptec psu just for the GPU or downgrading to a regular GTX 1650.

I could build my own external PSU using a Meanwell but this may exceed my own capabilities/knowledge.
 

DwarfLord

Trash Compacter
Oct 13, 2018
47
23
As it seems, the external pico psu (adaptec) likes to fail?! I try to power an i5-8400 + GTX 1650s + M.2 + 2x8GB RAM modules. Even at 70% power target and -100 on the core clock on my 1650s, my whole system suddenly shuts down at around 137-145w total system power draw.

Honestly, I run my 6pin via molex on the "accessories connector" which is not ideal and I could try soldering the 6pin directly to the power inlet, just to releave the pico 160xt. But is there a chance that it could work out?
I really want it to work and dont wanna by a second adaptec psu just for the GPU or downgrading to a regular GTX 1650.

I could build my own external PSU using a Meanwell but this may exceed my own capabilities/knowledge.
From what I understand, you were connecting your graphic card on the pico 160xt ?
If that's the case, yeah, you're asking too much from the pico 160xt. There is only 8A available on the 12v line, so 96Watts for the cpu AND gpu.