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Why is PSU end of ATX socket 20+4?


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Hi Corsair Forums


So I have a Corsair HX750 PSU and I noticed that the ATX 24 pin is solid on one end and split (20+4) on the other.


I understand that typically, the split end of the cable goes into the motherboard, to allow for boards with 20pin sockets.


However, with the HX750 it seems the other way round. The socket on the PSU looks like it's set up to take the 20+4 pin split. Why would this be and in what scenario would I need to only use one of the (20+4) split at the PSU end?


See 3 pics here showing how I've connected the cable to both the motherboard and PSU as well as the empty ports on the PSU for reference.


Many thanks for any expertise you're able to impart :)


P.S I'm using a Maximus XI Hero motherboard.

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Count the pins on the PSU side in your photos. That's a 9x2 connector and a 5x2 connector. Definitely not 20+4 on that side. It always requires both cables connected to both ends. I can't remember the last time I saw a motherboard that only required it. Looks like it was maybe 20 years ago? https://en.wikipedia.org/wiki/ATX
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uhm.. the PSU doesn't look at all like being done to take the 20+4 side... its a 18+10.


you'll always need both connectors on the PSU end. there are extra wires for voltage sensing at the motherboard's end in order to provide more accurate voltage.

As the motherboard draws more current, there are slight heat losses in the cables causing slight voltage drop. like the PSU may be sending a spot on 12V, but at the other end of the cable, the motherboard may only get 11.8v.

The extra wires are here to measure voltage at the motherboard connector to fine tune power delivery and get you your exact voltages.


I don't know if they are all for that.. maybe there's some cable doubling to allow for more current with less losses... but long story short, you always need the two connectors at the PSU end.

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