What wiring to use for PSU mod?

[Antioch]

Hi, everyone. Looooong time lurker, first time poster.

I'm planning on making a custom wire harness for my 300W PSU and would like to know what options exist for wiring. It's going into a SFF case, meaning that the routing is tight and space is limited, so I'm looking for a soft/flexible option that is easier to work with than the standard wires that ship with PSUs. Does anyone have any recommendations?

Also, is 21AWG braided copper wire too thin to consider? (As opposed to the default, thicker 18AWG wiring)

Cheers!

 

[Solo]

18 gauge, stranded. This is the stuff I use.

 

[Antioch]

Isn't 18awg braided what PSUs normally come with?

 

[Thehack]

Hi, everyone. Looooong time lurker, first time poster.

I'm planning on making a custom wire harness for my 300W PSU and would like to know what options exist for wiring. It's going into a SFF case, meaning that the routing is tight and space is limited, so I'm looking for a soft/flexible option that is easier to work with than the standard wires that ship with PSUs. Does anyone have any recommendations?

Also, is 21AWG braided copper wire too thin to consider? (As opposed to the default, thicker 18AWG wiring)

Cheers!

Ul1007 18awg is standard.

You can also use something like the M2427 Pico style plug in unit that works with atx psu to reduce a lot of the cabling.

18 awg is good for 8A. For cpu you can go with 4 pin instead of 8. GPU you can go with 6 instead of 8 as well.

 

[devinkato]

You're actually looking for something more flexible. I use silicon wire in my builds. They are so soft they're "floppy". They can't really be trained and bent permanently like for show cases, but they are so much more flexible and more easily routed in a case. Perfect for SFF.

If you're looking to sleeve or train cables, I'd stick with the standard wire recommended above.

 

[Thehack]

You're actually looking for something more flexible. I use silicon wire in my builds. They are so soft they're "floppy". They can't really be trained and bent permanently like for show cases, but they are so much more flexible and more easily routed in a case. Perfect for SFF.

If you're looking to sleeve or train cables, I'd stick with the standard wire recommended above.

Silicone is nice but be careful when unplugging connectors. Their max pull load is lower than standard plastic insulation.

I've also had silver plated wires made which are super compact but they too have pull issues. Easy for weaker crimps to manifest.

 

[Antioch]

Ul1007 18awg is standard.
You can also use something like the M2427 Pico style plug in unit that works with atx psu to reduce a lot of the cabling.
18 awg is good for 8A. For cpu you can go with 4 pin instead of 8. GPU you can go with 6 instead of 8 as well.

Yes, my motherboard uses 4-pin power connector, and I don't have a GPU so no concerns there. Thanks for the advice.

I had not seen your M2427 plug before (have bought your fan adapters in the past -- thanks!), it looks very interesting! Do you have a description of what the product is doing to reduce 24->7 wires?

Also, will it work with a different PSU with lower or equal wattage? Mine is a Seasonic 300W Gold 1U unit.

You're actually looking for something more flexible. I use silicon wire in my builds. They are so soft they're "floppy". They can't really be trained and bent permanently like for show cases, but they are so much more flexible and more easily routed in a case. Perfect for SFF.

If you're looking to sleeve or train cables, I'd stick with the standard wire recommended above.

Thanks for the silicone recommendation. Am not going to sleeve or train the cables. They just need to be easy to work with, tuck in neatly, and get out of the way.

Silicone is nice but be careful when unplugging connectors. Their max pull load is lower than standard plastic insulation.

I've also had silver plated wires made which are super compact but they too have pull issues. Easy for weaker crimps to manifest.

Ah, this is an excellent warning. My build will be a "set it and forget it" server that I don't expect to have to fiddle with the hardware for for 6 years (the machine it's replacing has been going for 7+!), so this may not be an issue, but is good to consider. Thank you for pointing it out!

 

[Antioch]

18 awg is good for 8A. For cpu you can go with 4 pin instead of 8. GPU you can go with 6 instead of 8 as well.

Do you think I can use a single 12V and GND wire that are double crimped on for the P4 (4-pin +12V power connector) on the motherboard to reduce the number of needed wires from 4 to 2? Or should I run 2x12V and 2xGND as is standard?

 

[Valantar]

Do you think I can use a single 12V and GND wire that are double crimped on for the P4 (4-pin +12V power connector) on the motherboard to reduce the number of needed wires from 4 to 2? Or should I run 2x12V and 2xGND as is standard?

That depends on the wattage of your CPU. Going off @Thehack's 8A number above, 1+1 wires will only be good for =<65W CPUs that adhere relatively strictly to their TDP for max power draw (which is rare these days). 12V8A is 96W, but you need some headroom unless you want to risk overheating wires and melting connectors and/or insulation. For anything running long-term I'd go for 2+2 for safety, no matter what.

As for 21AWG it is half the cross section area of 18AWG, so that's definitely not recommended unless you add more wires for safety.

Beyond that, AWG alone isn't an accurate indicator of how thick or stiff the cable itself is - as the examples above show the insulation makes a big difference. There are also wires like MDPC-X that are specially designed for maximum copper in as thin a wire as possible - but they are pricey.