Parts and progress for my sons SFF gaming PC

[BobGarn]

So I have been emailing with Larry from HDPlex trying to wrap my head around what I need and don't need I have resorted to creating a drawing in Paint to try go visualize it.
I am correct in understanding that I need a DC-DC board (as far as I know that's what they are called) and then I would also need an external AC adapter (since there isn't much room in the case)

 

[GuilleAcoustic]

Regular computer PSU (ATX, Flex, TFX, SFX, etc.) are AC-DC. They get AC from the main (wall plug) and output ATX compliants DC voltages (24pins ATX, 4-8pins CPU power, Sata power, PCIe power, etc.)

HDplex and alikes are the same, but they take DC voltages as input (batteries, laptop power bricks) and output ATX DC voltages. With that kind of PSU, you'll need as AC-DC source (internal or external) as you can't feed them with AC from the wall plug.

 

[jØrd]

I am correct in understanding that I need a DC-DC board (as far as I know that's what they are called) and then I would also need an external AC adapter (since there isn't much room in the case)

yes

 

[BobGarn]

So another update on this (sorry)

Will I need to use the 8-pin CPU/EPS connector on the motherboard? I'm asking because there is not corresponding connector for that on my DC-DC board.
I am not planning on putting a high-end CPU or any other demanding parts for that matter, in the machine

I have attached a picture of the connector just so we are all on the same page

 

[GuilleAcoustic]

Which DC-DC did you get ?

The 8pins is not mandatory, but I am 99.9% certain that you must at least plug a 4pins CPU power cable.

Below is a tutorial on "how to plug a 4 pins CPU power into an 8 pins connector"...

 

[BobGarn]

Oops... I got this one https://it-tech-uk.com/collections/...rd-htpc-250w-12v-pico-psu?variant=28699911506
On that DC-DC board there is a 4-pin for the power in (I assume) and another 4-pin next to the 20-pin

 

[tinyitx]

The User Manual of your motherboard mentions on page 14 that:-
''The 12V power connector mainly supplies power to the CPU. If the 12V power connector is not connected, the computer will not start.''
It looks like the connector is a 2x4 12V connector and so using one 4-pin mentioned above might work.

 

[BobGarn]

Yes I read the manual (should have said that to begin with) and saw exactly what you mentioned @tinyitx and that is one of the reasons why I'm asking about it. The way it's formulated in the manual made it sound like there is no way I'll get it to work without power to the 8-pin connector

 

[GuilleAcoustic]

Your DC-DC has 12V 4pins, so you might be just fine.

 

[BobGarn]

If you mean then one highlighted in red in the picture here then as I understand it is for the power in. The other one highlighted in green is the 20+4-pin

 

[GuilleAcoustic]

Don't underestimate my Google Image power

 

[BobGarn]

Ah @GuilleAcoustic so I don't necessarily need to use the 4-pin from the 20+4-pin, I can use the 4-pin from there to power the 8-pin CPU/EPS?

Well why should it be easy

 

[GuilleAcoustic]

The 20+4 pins is for the motherboard ATX power. Older motherboard had 20pins while newer have 24pins.

http://www.playtool.com/pages/psuconnectors/connectors.html#atxmain20

Long story short...

You can plug a 20 pin ATX power cable into a motherboard with a 24 pin ATX connector[...] The 24 pin motherboard connector is actually just the 20 pin
connector with 4 extra pins added on the end. The original 20 pins were unchanged The extra 4 pins are not separate rails. They're just extra lines to provide more current to the same rails. [...] I've never heard of exceptions
and it doesn't make sense for motherboard makers to create any.

and...

A 20 pin power cable only fits into one end of a 24 pin motherboard connector
so you can't insert it incorrectly.

however, it appears that there is no current limiting on a 20 pin ATX PSU, as I assumed there would be...

They added those extra 4 pins for a reason. When you plug a 20 pin cable into a 24 pin connector you're not providing the extra current carrying capacity which may be needed by the motherboard. If your motherboard's current requirements are low enough then it will work properly with only a 20 pin power cabled plugged in. But if the motherboard draws enough current, then you can overheat the 20 pins you're using on the 24 pin connector. I've seen enough pictures of burned ATX main connectors to assure you that this happens. [...] Connectors really do get hot if you overload them so the safest thing to do is use a real 24 pin power supply on a motherboard with a 24 pin connector. Note that your 24 pin machine
may work fine with a 20 pin power supply until you add a PCI Express card later on down the road. PCI Express cards can draw up to 75 watts through the
motherboard connector so adding an expansion card can substantially increase
power draw through the main power cable.

Lastly, as an aside:

If you have an ATX power supply with a 24 pin main cable, it's okay to plug it
into a motherboard with a 20 pin connector.