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Why are computer power supplies like this?

I noticed this before and again last night. I am changing plugs from a bad supply to a good one. There is a connector with 20 or so wires that plugs into the motherboard. 6 different color wires. But all the wire of a poarticular color go to the same trace on the power supply circuit board. So all the reds to one trace, all the yellows to another trace and so on. So why all the different wires to the motherboard? It can't be just because it is harderfigure out how to route the traces. A bigger connector with more wires costs more money and every computer I've seen is the same. Thanks, Eric

Reply to
etpm
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Current capacity, yet flexibility? ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
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Reply to
Jim Thompson

snipped-for-privacy@whidbey.com wrote on 11/3/2017 12:20 PM:

Computers use a lot of power. The voltages are low, so the currents are high. A high end CPU alone can burn 100 watts. That is over 8 amps of current at 12 volts. To carry that current the connector contacts would need to be large. So they use multiple contacts and so multiple wires. This also provides redundancy so if one contact is poor with a high resistance the others can still carry the current.

The standard for this connector has evolved over the years and there is a degree of back compatibility with lower power machines. Isn't the connector actually two connectors, the smaller one optional? Or did they update the standard again? Or am I just not remembering it correctly?

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Rick C 

Viewed the eclipse at Wintercrest Farms, 
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Reply to
rickman

The last few machines I have worked on have only 1 big connector going to the motherboard. I don't remember what the older machines were like. You're explanation makes sense. Thanks. Eric

Reply to
etpm

Compatible replacements have two plugs, and they interlock together.

Reply to
jurb6006

Someone recently gave me a HP PSU - its more or less the same form factor as an ATX PSU, but it has just 2 high current 12V outputs and a few other wires.

Reply to
Ian Field

Ian Field wrote on 11/6/2017 3:16 PM:

Does it have special contacts for the 12 volt power connections? Typical pins are only 1 or 2 amps. So for a 100 watt draw it would need at least 4. To get more like 4 amps per pin would require contacts with a higher current rating and so likely larger, perhaps blades rather than round pin and sockets.

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Rick C 

Viewed the eclipse at Wintercrest Farms, 
on the centerline of totality since 1998
Reply to
rickman

I that a computer supply, or is it for some HP test equipment.

Reply to
Michael A Terrell

Molex claims 6.5A per contact for the nano-fit connectors used to connect power to PC motherboards

For the CPU there's a separate cable with 4 or 8 contacts half are ground the other half 12V

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Reply to
Jasen Betts

Molex claims 6A or more per contact for the "Mini-Fit Jr." connectors used to connect power to PC motherboards

For the CPU there's a separate cable with 4 or 8 contacts half are ground the other half 12V

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This email has not been checked by half-arsed antivirus software
Reply to
Jasen Betts

Maybe some obscure test instrument uses an ATX form factor PSU, that never occurred to me.

Reply to
Ian Field

The company does want to encourage you to buy a new one.

Parts are cheaper, smaller and more difficult for non manufacturing or service people to replace every day.

Reply to
bruce2bowser

Apparently, HP/Agilent uses them. I see question on the HP/Agilent Yahoo group about failed SMPS with them.

Reply to
Michael A Terrell

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