What PSU is usually used in mini-ITX cases/chassis

casechassismini-itxpower supply

The mini-ITX computer will be a general use computer. Not a dedicated HTPC or Home server.

In general use mini-ITX cases, what PSU form factor is usually used? I understand that some case manufacturers provide custom built PSU to fit their case but I prefer to get the ones that use a PSU that follows standard form factors in case a replacement is needed.

For example, what PSU fits into general purpose cases by Lian Li?

Am I to assume that smaller PSU form factors also affect the possible maximum output?

Best Answer

Wikipedia says

The Mini-ITX standard does not define a standard for the power supply ...

Which means size and layout of PSU depends only on the case.

... though it makes some suggestions of possible options. Conventionally Mini-ITX boards use a 20- or 24-pin "original ATX" power connector. This is usually connected to a DC-DC converter board which in turn is connected to an external power adapter. Generally both the power adapter and the DC-DC board are supplied with the case.

An Intel document suggests

Provided the very different needs of the platforms that fit in the small desktop form category, this specification does not attempt to define a standard for the power supply to match with the Mini-ITX motherboard specification. Instead it recommends that manufacturers consider using a:

  • SFX, TFX or FlexATX are available power supply form factor for chassis greater than 5 liters
  • External power adapter for chassis less than 5 liters

P.S. Mini-ITX inside a PSU!

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