Connecting dual gpu with adapter 4 molex (1 is white) to pci

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computingandrebooting

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Jun 26, 2017
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Hello, I am trying to hook up a second video card to my PC.

I'm currently running 1 ati Radeon HD 5850. I have a second card here same exact thing, and here is the problem. My psu is a fatal1ty 700w and it has only 2 6+2 pcie pins.

Each 5850 video card requires 2 6 pin pci pins. So I see I'm short two 6 pin pci's. Which is a huge bummer.

Anyway, ive been doing a lot of research about splitters and adapters and see they aren't recommended. However, my psu came with some (2 molex -to-1 6pin pci) adapters and I think I may have everything I need to fix this problem. If it came with psu it must be ok to use?

I will need four free molex connections to make this work. Which it appears that I have my only concern is that 3 of my free molex are black and the 4th is white!

So does it matter that one is white? What is the difference between a black 4pin molex or a white 4pin molex? Is there a difference? Will this set up work for me? Does anyone see any potential problems?

Any help is appreciated as I'm right in the middle of this project and am awaiting some input.

Thanks

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Solution
Karadjgne
Those pictures just came in. That's a mess. From the looks, all 4 of those black molex are on the same chain, the white one is just an extension of one of the black ones? You can see other white molex extensions above. That's not going to work. Way too much load on way too small of a wire. There's reasons why a 6pin has 2x yellow 12v leads, and you are wanting to power 4x 12v leads via a single 12v source.

If you want to sli, replace the psu. What you want, and what's going to happen are 2 different things in this case.
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Karadjgne

Karadjgne

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Potential issues abound. That 18ga power lead that those molex are connected to is good for @10A, that's 120w @12v. You propose to use 2x molex per chain (hopefully just 2x) as each molex will see 60w. While splitting the connections and using 1x pcie and 1x adaptered pcie might make sense, realistically the bottom card doesn't work as hard as the primary, so the adaptered pcie should stay below on the single bottom card. Just don't use any more than 2x molex on each chain or you'll be in trouble, quick.
As far as I can tell, there's no difference, I found no references to a white molex anywhere, all the psus I found had all black/red connectors. Only reason I can think of that 1 is white is it might have been a refurbished unit, and that was a bad connector that just got replaced.
I'd be happier if you just replaced the psu, newer 600w+ usually have 4x 6+2. The lack of pcie connectors on a 700w unit is somewhat a dead giveaway that the unit isn't trusted even by the manufacturer to power sli/crossfire loads requiring the use of 4x pcie connections.
 
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Karadjgne

Karadjgne

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Dec 26, 2012
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Those pictures just came in. That's a mess. From the looks, all 4 of those black molex are on the same chain, the white one is just an extension of one of the black ones? You can see other white molex extensions above. That's not going to work. Way too much load on way too small of a wire. There's reasons why a 6pin has 2x yellow 12v leads, and you are wanting to power 4x 12v leads via a single 12v source.

If you want to sli, replace the psu. What you want, and what's going to happen are 2 different things in this case.
 
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Solution
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computingandrebooting

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Jun 26, 2017
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Well that is a shame. thanks for your replies. I really do appreciate it. Wish I would have realized this sooner, now I have an extra GPU that I cant use. If I buy a new power supply I'll have to rewire the entire computer correct? Can anyone recommend a cheap power supply that will work, im not even sure what to search for to find what i need at this point? Four 6-pin pci power supply isnt really turning up much for results. Frustrating. I think im going to call it a night. thanks again everyone.
 
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