Newb question about DC to ATX converters

[extracampine]

Bit of a newb question here reading PC power supply. I understand that the wall supply is AC - alternating current. I understand that PC components require a DC, direct current.

 

I was looking at the HDPLEX linear PSU, which has 4 rails of DC at 4 different voltages to power a PC.

 

So what is the role of a DC to ATX converter? Why can't the outputs from the HDPLEX linear PSU be connected directly (with the correct adapter cables) to the motherboard slots? Why is the HDPLEX (or similar) DC to ATX converter apparently required?

 

Thanks

[Hifidelit]

They can be fed directly with some motherboards and the picoPSU or HDPlex dc-atx can be discarded. Some motherboards won't work though or are tricky to get working and it's a more complicated process having separate feeds to the pins. Some discussion here of it towards the end:

Linear Power Supply for Pico PSU - Anyone done this? - Computer Audio - JPLAY - hi-end audio player for Windows

 

There are also some PSUs such as Core Audio Technology or Teradak who have full linear atx supplies.

ATX Linear Power Supply | Audiophile 10-rail ATX Power Supply for Computers and Music Servers

 

The picoPSU or HDP dc-atx is a convenient way of getting the power to the atx socket on the motherboard and enables the easy use of a linear ac/dc PSU such as the HDPlex etc.

 

See the power supply section here:

ATX - Wikipedia, the free encyclopedia

PS_ON# or power on is a signal from the motherboard to the power supply. When the line is connected to ground (by the motherboard), the power supply turns on. It is internally pulled up to +5 V inside the power supply.