Proper way to make Molex cable harnesses/splitters?

[Red Squirrel]

I ordered the parts and tools needed to make Molex connectors using Mini Fit Jr. Wondering what is considered the appropriate way to make Y cables, can you just double crimp on the same input pin? Or is it best to splice the wires together, solder and shrink wrap? Obviously need to be concerned about the amperage if I split too many times as well, 18 awg is good for what, around 12 amps I think? So an 8 pin would do about 48 amps give or take? Probably want to slightly derate that as it's not guaranteed all conductors will share the load equally.

This would be for GPUs/mining so need to do it right considering the amount of current going through. Yeah you can buy them, but what's the fun in that? I also been wanting to play with Molex and different connector types anyway for other projects that may make use of them.

 

[bruceb]

If they are miniature size molex pins, I would splice the wires and solder, then heat shrink, then crimp the terminal end. Most terminals are really only designed to hold one wire properly at a time, unless you have enough connector size to allow proper wire crimp and wire strain relief. This link tells all you need to know

http://www.molex.com/tnotes/crimp.html#top

 

[Red Squirrel]

Yeah found that while searching actually. I was kind of thinking I probably can't double crimp, so guess I will just solder and shrink wrap.

 

[Red Squirrel]

Boo so turns out 4 pin connectors on VGAs are not actually standard 4 pin molex. There's a bunch of sense wiring wizardry going on and the indentations are different. Was hoping I can just make my own cable harnesses. Some of those cables bought online are like 20 bucks a pop and some video cards have like 2 connectors! I'm sure I can find those special connectors on Digikey though, but they may also be custom to the computer industry. Anyone familiar with that? I rather make my own if I can.

The stuff I bought is not a loss though given I had been wanting to play with Molex connectors anyway for other projects, and thankfully the modular PSU does use standard molex coming out, so I can still make extension cables and what not. Just need to watch voltages if I decide to make splitters. The +12 should be on the side opposite to the clip but who knows how some modular PSU makers may choose to make their cables so going to have to watch. But for a simple extension cable then it won't matter. I'd imagine they would try to stay standard though.

 

[VirtualLarry]

The last "4-pin" power connector that I used on a VGA card, was back in the days of AGP.

Current-gen PCI-E cards, use either 6-pin or 8-pin (6+2 pin).

Can you clarify what you're seeing?

Some powered risers use either a molex 4-pin, or a 6-pin. AFAIK, thr 4-pin molex on those, IS the same as an ATX PSU's 4-pin Peripheral connector.

 

[Red Squirrel]

I meant to say 6 pin and 8 pin. Basically, the pin out is odd, I figured it would be 12v on one side and ground on other, and that it would just use standard indents for those connectors so that if I crimp a 6 pin or 8 pin it would fit. But turns out there's some sense wires and stuff and the connectors don't actually match up. Was hoping I can just make my own GPU fan out cables.

 

[dave_the_nerd]

I've purchased plenty of Y-splitters that are double-crimped. As long as you're not pulling too much amperage for the wire gauge in question, you'll be fine using a thinner wire. (So low-watt stuff like fans and LEDs - and even SSDs and some HDDs - can be run on thinner wires.)

Amperage rating should be printed on the wire insulation. Otherwise you can look it up based on gauge and wire type (stranded, solid core, etc.)

If you're talking 6 or 8 pin PCI-E connectors, well... don't double-crimp those and don't use thin wires. They can pull a lot of power.

 

[Red Squirrel]

Yeah I crimped a standard 8 pin extension just for practice, and there's no way you would be able to double crimp 18 awg so if I make splitters I'll want to just solder and heat shrink. GPU ones are odd though, the notching and pin out is different than what one would expect, not sure if you can buy those connectors separately to crimp your own. It's Mini Fit Jr. but different notching than the connectors you'd buy off Digikey. Can't seem to find much info on it or if they are called different. The pin out is also odd, the difference between 6 pin and 8 pin is basically that 8 pin has two extra grounds. you'd think it would also have an extra positive. The sense lines are just grounds, from looks of it. Basically it's so the card knows if it's a 6 pin or 8 pin.

But yeah don't want to have too many amps per circuit. I'm getting different numbers doing research, anywhere from 9 to 13 amps for 18awg. Probably don't want more than 3 GPUs per 8 pin connector and that might be pushing it slightly, but active airflow would probably keep it within a safe zone. Amp ratings are based on wiring that is not actively cooled.

 

[Red Squirrel]

So I found the proper connectors for GPUs: https://www.ebay.ca/itm/30pcs-4-2mm...088956?hash=item3f81a624fc:g:yh8AAOSw-ldZZMvv

This will allow me to make my own wiring harnesses that fit on GPUs. These have different indents than standard 6 and 8 pin discrete connectors. My PSU only came with 4 connectors, and some cards take 2 on their own. So I will make some splitters basically. You can buy them but cheaper if I can make my own. Heck I might make and then sell some myself...

 

[dave_the_nerd]

So I found the proper connectors for GPUs: https://www.ebay.ca/itm/30pcs-4-2mm...088956?hash=item3f81a624fc:g:yh8AAOSw-ldZZMvv

This will allow me to make my own wiring harnesses that fit on GPUs. These have different indents than standard 6 and 8 pin discrete connectors. My PSU only came with 4 connectors, and some cards take 2 on their own. So I will make some splitters basically. You can buy them but cheaper if I can make my own. Heck I might make and then sell some myself...

That's actually a surprise.

http://www.ebay.com/itm/like/112627317116

 

[Red Squirrel]

That's actually a surprise.

http://www.ebay.com/itm/like/112627317116

Wow that's better than the ones I was finding. They were like 20 bucks a pop when I was searching. Which prompted me to just buy the hardware to make my own.