The Mini-ITX Ironclad Plus is compatible with PSUs that comply with the ATX standard that use the 20-pins or 24-pins connector, so almost any would do, but there are some minimum requirements to keep in mind.
A fully assembled Mini-ITX Ironclad Plus only pulls about 9 Watts from the wall while running heavy MiSTer FPGA cores, that’s a very low power consumption compared with ATX power supplies everywhere providing 160+Watts!, Ok, that’s true, but the usual DE10-nano power requirements still apply here and it needs a PSU capable of providing about 2 amps from the 5 volts line, just like the PSU that came with it, or even more Amps if you are going to use high power consumption USB devices, like big mechanical hard disks for example which might need another 2 amps just for themselves to start spinning.
Fortunately that 2 amps are a piece of cake for most ATX power supplies, for example, the typical 80 W Pico-PSU provides 6 Amps at its 5 volts output:
picoPSU-80 DC/DC PC ATX power supply (Fanless, 80 Watt) [ PicoPSU ] (cartft.com)
So it is pretty easy to choose a PSU for your Ironclad Plus, if you can see its full specs go to the 5v output and check how many Amps it can provide, if not, just pick one in the range of 120-160 Watts which is plenty of juice and i have never seen one which does not greatly exceeds the 2 Amps from the 5 volts outputs.
TIP: This power supplies usually come with additional connectors, like 4 pin molex for hard disks and floppys, sata power connectors, 4 pin CPU connector, etc. Those connectors have no use in your MiSTer Mini-ITX Ironclad setup, if you know you are not going to use that PSU for other setup in the future, you can just cut them out from their wire’s base while it’s completely unplugged from the wall to make your build cleaner.
The power “brick”: This small PSUs usually come with an external 12v power “brick”, if that is your case, just use that, if you have to purchase one or have one of them at home, 12 volts with 2 Amps at the output is more than enough for the usual MiSTer Mini-Itx Ironclad setup.
