Power Supply Single output Mean Well PSUs + DC-DC ATX converter = High wattage SFF?

[Sure_Sh0t]

Power supply + output stage

I think this combo should work because these types of power supplies have adjustable voltage output via potentiometer so you can get input voltage within spec for the converter.

If that is so it opens up a lot of possibilities for power density in SFF scenarios.

It would be rather beefy but you could conceivably make a converter with 1000W capacity. Which would be overkill for SFF, but you could make full size ATX builds smaller that way.

 

[Kmpkt]

We've already had some members do this mod. @Thehack has a guide over here.

https://smallformfactor.net/forum/threads/meanwell-psu.1270/

I'd say the biggest drawback for most of the crew here is the size of that unit combined with the fact that there are no DC-DC boards that can do over 500W. I am developing a DC-DC right now that will take about 500W at maximum and by daisy chaining DC boards should be able to take up to 800. I hope to reveal it sometime in the next few weeks and I would love to see someone do a high wattage application like this with it.

 

[Thehack]

At 295mm x 127mm x 41mm, it is much larger than an SFX-L power supply even, not including the DC-DC board you have there.

At that point, you can go for an SFX-L 800W platinum and get better power density.

 

[EdZ]

combined with the fact that there are no DC-DC boards that can do over 500W

I wonder how stable running multiple PSUs in parallel could be. From a common AC-DC source it should be reasonable, with the ground shared between both 'rails' then there should be minimal current flow between outputs (enough that, if needed, diode protection would be reasonable). Sharing AC-DC solutions (or any '12V' system) might be a bit trickier to ensure PSU protection.

 

[Thehack]

I wonder how stable running multiple PSUs in parallel could be. From a common AC-DC source it should be reasonable, with the ground shared between both 'rails' then there should be minimal current flow between outputs (enough that, if needed, diode protection would be reasonable). Sharing AC-DC solutions (or any '12V' system) might be a bit trickier to ensure PSU protection.

If anything... I don't see why would go for anything besides 12V if you go for a meanwell. And if you do go for a high power build, most of the output exists on the pure 12V so a dc-dc board that supports high wattage isn't required

 

[EdZ]

If anything... I don't see why would go for anything besides 12V

X-post:

Plug-in DC modules' 'goodness' is more important if you're using a 19V supply. If you're using 12V, then those modules are almost entirely acting as a passthrough for 12V, and only need to deal with 3.3V and 5V loads (which are pretty tiny for modern PCs), so is only handling the conversion a few tens of watts at most itself. But at 19V, the plug-in modules needs to do the work of converting all the power the machine is using.
Conversely, if you're using 12V then you're in theory a little more vulnerable to the foibles of your 12V AC-DC solution. If it can't handle peak current, there's nothing the plug-in module can do about it. At 19V the presence of a DC-DC converter means some current spikes will be 'smoothed out' to below the level that would trip out the AC-DC solution.
But in practice, I suspect 19V is more vulnerable to peak transient loads. 19V AC-DC bricks are almost universally laptop PSUs, so not intended to handle power spikes at all. 12V AC-DC supplies in general seem to be designed to be more tolerant of a wide range of load behaviors, because they're not aimed at charging laptops but instead powering equipment directly. The tradeoff is that laptop bricks are mas-produced so can be had cheaply, whereas 12V AC-DC supplies are less common and generally aimed at a market with higher margins, so more expensive.

tl;dr:
19V: Cheap bricks, more expensive plug-in modules, more heat generated by plug-in module, vulnerable to power spikes.
12V: More expensive AC-DC solutions, cheap (er) plug-in modules, less heat generated by plug-in modules, potentially less vulnerable to power spikes (down to your chosen AC-DC solution to handle).

 

[Thehack]

Exactly. Anything besides 12V when considering a meanwell PSU is just counter productive. 19V power just adds complexity and heat problems.

 

[Kmpkt]

The biggest barrier to using a Meanwell 12V right now is the lack of DC-DC options. As far as I know, the only choice we have is G-Unique (which is not a bad thing).

 

[|||]

Mini-Box has been the go-to option for 12V DC-DC, since G-Unique's attainability hasn't been reasonable until recently.

 

[Kmpkt]

While I would love to see a fully 12V system at some point in the future, right now I think the lack of hardware selection is just too significant to use it.