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I'm planning to use an ATX power supply to power a small set of 12v devices. I've read plenty of guides about adapting ATX -> bench supply, but I can't seem to find any mention of the connector material for the pins themselves.

I'm primarily interested in the ATX12V 8-pin connector, but the same question also applies to the ATX 24-pin. I'd like to connect directly from the 8-pin connector to a device without going through a board first, so just wire-to-wire.

I've found the appropriate housing parts from Molex: (8-pin and 24-pin).

The documentation for both of those housings lists the compatible connector pin types (it's the same pins for both). The problem is that I have no idea which pin material to choose. Broadly, the options fall under tin or gold, and within each of those two categories, there are several sub-choices. For example, there are many choices for 16 awg pins.

My understanding is that gold coating is better for many reasons, but more expensive. However, gold/tin matings are the worst. This is a small scale project, so I'm not worried about the cost. I don't want to buy gold if the PSU pins are tin and vice versa. I've been unable to find any documentation to suggest which of these materials is used (either mandated by spec or just typically in practice).

TL;DR:

  1. Does the connector pin material matter (tin vs. gold)?
  2. If so, which should I get for interfacing with a standard mid-to-high-end ATX power supply?
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  • \$\begingroup\$ If this is sitting in a dry house for a few years either is fine. If this will be used in a high humidity, or near ocean environment for 30 years... Then you need gold to stop the corrosion that will occur with the bare tin. \$\endgroup\$ – MadHatter Aug 12 '20 at 20:38
  • \$\begingroup\$ Thanks, this will be sitting in a standard computer case in an office-like (climate controlled) environment -- nothing fancy. Are you suggesting that in such a setting, even if I buy the "wrong" type of pin (e.g., I buy tin and the PSU is gold), it won't make a difference? \$\endgroup\$ – Kevin W. Aug 12 '20 at 20:40
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    \$\begingroup\$ Look at the ATX power supplies or motherboards. Do they have gold plated connectors? I don't recall ever seeing, so non-gold plated must be fine for consumer products. \$\endgroup\$ – Justme Aug 12 '20 at 20:40
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Does the connector pin material matter (tin vs. gold)?

They need to be matched, if you are worried about 10mΩ's of resistance, then use gold for most digital electronics this won't matter. Even with 2A of switching current (which would be worst case) this would only be in the 10mV range which wouldn't be a problem for digital noise.

If so, which should I get for interfacing with a standard mid-to-high-end ATX power supply?

Go with gold to gold or tin to tin, otherwise you could get corrosion in humid environments.

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  • \$\begingroup\$ Thanks! I understand that I want them to match, the problem is that I only control one end of the mating pair, and the other is determined by the PSU. I don't know what material the PSU is. That's what I'm trying to ask here -- which type of pin should I buy to achieve a match? \$\endgroup\$ – Kevin W. Aug 12 '20 at 22:41
  • \$\begingroup\$ meta.stackexchange.com/questions/126180/… \$\endgroup\$ – Voltage Spike Aug 12 '20 at 22:41
  • \$\begingroup\$ Look at the pin, then look at the other end on the device or mobo, they should be matched \$\endgroup\$ – Voltage Spike Aug 12 '20 at 22:42
  • \$\begingroup\$ I'm a new user, so upvoting doesn't seem to do anything. I guess I should stop writing 'thanks' though...? \$\endgroup\$ – Kevin W. Aug 12 '20 at 22:43
  • \$\begingroup\$ It doesn't give rep, but it still counts, you vote on the answer not the question, make sure you vote on questions you like and when someone answers a question, you mark it answered \$\endgroup\$ – Voltage Spike Aug 12 '20 at 22:44

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