I made a size comparison of the different power supply solutions available which are capable of >=200W output.
If you keep in mind that the DC-DC solutions still need the corresponding AC-DC unit to work, you wont safe any space in your case if you put the AC-DC part inside. You could just buy a FLEX PSU.
some examples (not considering cables and connectors):
HDPLEX 400W Set internal mounted: 0,43 liter + 0,20 liter = 0,63 liter
FLEX 400W (non modular): 0,54 liter
HDPLEX 200W Set internal mounted: 0,43 liter + 0,05 liter = 0,48 liter
RCC-COOLMOD1 & RCC-PWR1 400W Set internal mounted: 0,55 liter + 0,04 liter = 0,59 liter
Long story short: my initial idea was to provide a solution for you to build a small, nice looking and powerful external AC-DC unit for powering 12V DC-DC ATX boards. 1st to make up space in your cases and 2nd to get rid of that chunky DELL adapter which is one of the few available solutions except some also chunky LED drivers.
To come back to "robbee's" question before: you are right. If you need some internal solution for 400W, better get a ENHANCE FLEX PSU, put a Noctua fan in it and you are good.
bad news / good news update
I didn't consider the production tolerances of the PCB and the aluminum extrusion case. The power supply I got for testing is slightly larger and the inner dimensions of the extrusion slightly smaller. That means there is not enough space for my FR4 and Lexan insulators. And as someone on reddit was jocking: no, I do not want to get anybody killed.
Long story short: I would have to increase the overall dimensions of the case and that would clearly make it less attractive in terms of size compared to available options.
as I have learned during my tests, the RPS/EPP-400 & RPS/EPP-500 will provide you with up to 90% of the rated max. output power if your case is well enough ventilated (e.g. the PSU sits somewhere near the intake fan). So if you want to go for internal, you do not need some additional cooling mod, just get the normal version with the protection "cage" and don't forget to put a ground (earth) connection somewhere on the chassis.
Should there be interest for some external solution (turn the RPS and EPP into an external brick) , just let me know. Else I will close the project.
Is that extrusion custom or off the shelf?
Also, consider that the enhance 7660b can be customized.
And Adapter tech released their 300W external GAN unit.
Both of the above units can be had with enough moq. COnsidering after all the engineering and assembly work you have to do, check out how those options compare.
How much bigger would this make it? Or maybe just provide additional cooling options for the cage version?
Stock some adapters for FlexATX to Meanwell tooIf going with another extrusion case, the next bigger size I have available would be 10mm wider and 4mm higher.
But I just had another idea...
How about a bracket to make these kind of PSUs mountable to an standard SFX cutout? Could probably also include a small fan holder somewhere in this design? And you could mount it facing inside or outside on your cases.
Would this make sense?
This may lead me to the idea: sandwich mount, usually put their psu between bottom and top fan, so why don't we make a open-air psu case for this? Since then, It may help many custom waterblock build to show off their cases without negative heat from the psu.It depends if there is a direct airflow from the case fans. Otherwise it may cause hot air pockets in the case.
I think open design like some lightweight gaming mice will make it look more unique, also it will have room for another air flow from case fans.
I mean, the external case for any sff psus, nearly like what seasonic did with their ATX titanium psus https://seasonic.com/prime-titanium-fanless, but still have space for a 92mm fan. The benefit for sandwich case is that air blown from bottom fans can't be block, it would go through the power supply and go up.Not sure if I get your idea.
You can already buy it of the shelf with a meshed case.