Question PCIe cables question

johnrob

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I have two 8 pin PCIe cables but I need a 6 pin cable for a new GPU that I'm getting. From what I've read pins 1,2,3 are +12v and 4-8 are all ground cables.

I do not have the oem cables anymore.

Would it then be okay to make a cable where 1,2,3,5,6,7 go to a 6 pin connector and pin 4 loops back to pin 8 on the PSU side?

If I had a 6+2 cable I would just zip tie it down, but the GPU connectors I have are a solid 8 pin 6+2 block, I can't disconnect the +2.

PSU is a Corsair RMx 750 white edition PSU.
 
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Vic 40

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If I had a 6+2 cable I would just zip tie it down, but the GPU connectors I have are a solid 8 pin 6+2 block, I can't disconnect the +2.

PSU is a Corsair RMx 750 white edition PSU.
Those +2 should be separable from the 6pins. Thinks you're not looking at it the right way, maybe somehow have the cables wrong and looking at the psu side.
 

johnrob

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Sorry, these are custom cables, I used solid 8 pin connectors and do not have the original 6+2 connectors anymore.

Just trying to figure out the right way to make a 6 pin cable for my new GPU.
 

USAFRet

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Sorry, these are custom cables, I used solid 8 pin connectors and do not have the original 6+2 connectors anymore.

Just trying to figure out the right way to make a 6 pin cable for my new GPU.
"Custom cables" ?
And then you're going to modify them further?

Be prepared for a little mushroom cloud out of the top of your case.
 

Darkbreeze

Retired Mod
I'm just trying to find out the best way to reduce an 8 pin from the psu to a 6 pin on the GPU
You don't. ALL of the graphics card 8 pin connectors (Aside from MAYBE a VERY small handful that ACTUALLY had 8 pin PEG/PCI connectors, but never do anymore) are actually 6+2 pin connectors and have been for a considerable amount of time.

All of the EPS connectors are generally 4+4 and cannot be used with graphics cards anyway, besides which they are not actually "8 pin" either. So in reality, there shouldn't BE any "8 pin" connectors anywhere on any modern power supply. Most especially, there are none on the RMx 750. They are 4+4 EPS CPU 12v and 6+2 PCI/PEG. There shouldn't be ANY need to modify or otherwise adapt ANYTHING, at all, period.

And before you come back and say "Well, mine is", no, it isn't.
 

johnrob

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Nov 22, 2014
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And before you come back and say "Well, mine is", no, it isn't.
Well, mine is.

I can't seem to get my photo to upload but the connector on the GPU side is a single piece 8 pin block with the notch and pin shapes for a 6+2. so it's a 6+2 but it's permanently attached in an 8 pin configuration that won't work for a 6 pin GPU. That wasn't a problem for my 2x 8 pin 5700xt, in fact I chose that on purpose because it looks much cleaner. It won't work for my 6+8 gpu that's on the way, however.
 

Darkbreeze

Retired Mod
It's NOT permanently attached, it is intended to "snap" apart if only the six pin is required. Many units, in fact, almost all, come that way with the EPS connectors as well. They SEEM to be a solid 8 pin connector but in reality they are a 4+4 pin connector that breaks in half if you only need the 4 pin EPS 12v connection OR in the even you have a board with the need for an 8 pin AND a 4 pin, and your PSU has two similar EPS connectors, you can use one complete 4+4 pin and half of the other one. It is no different for the 6+2, which by the way, SAYS so RIGHT ON THE DAMN POWER SUPPLY, as seen on the Corsair product page for the RM750x.

CLEARLY PRINTED, 6+2 PCI and 4+4 CPU.






And, in the user manual, where it specifically ALSO says 6+2 and 4+4. No where, at all, ever, does it say anything about there being ANY kind of 8 pin only PCI or EPS connector, because as I said, other than a very few units in the entire HISTORY of power supplies, there aren't any that traditionally have come that way. A few, and this unit is not one of them. So, like I said, no, it isn't.

 

Vic 40

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Well, mine is.

I can't seem to get my photo to upload
You can use Imgur to post a picture here,use the "img" link.
Click "new post" ->choose "upload images" -> "browse" ->choose the picture and click "open" ->put cursor on the picture that you uploaded->choose "share links" and copy the img link,paste it in your next post.

@Darkbreeze,

Think he has custom cables like from cablemod where he chose to have only 8 pin connectors.
 

Darkbreeze

Retired Mod
Derp. I totally missed that he bought custom cables, so I guess that part is my bad. Regardless, you use the ORIGINAL cables that came with the PSU until you can BUY a new custom made six pin cable, likely, from the same company you bought the original kit from. Or, if you know what type of sheathing was used, whether it was paracord or one of the sleeving specific products like Telios, then from another maker that uses the same material.

If you have experience making custom sleeved wires and you have all of the tools to release the cable ends, and have a no-doubt-about-it pinout diagram or the knowledge of which pinout needs to be what, AND a replacement six pin connector, then it shouldn't be a problem, but if those things were true you wouldn't be here asking us to relieve you of the responsibility that would come with making the decision on what needs to go where and why by saying "sure, go ahead", you'd have just already done it.

There are absolutely guides on resleeving your cables. The ones by Lutro0 from Mainframe customs are particularly good and Mainframe customs as well as Cablemod are both good resources for such materials and information.
 

johnrob

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Nov 22, 2014
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I made the cables by using tools to remove the pins from the corsair pcie connectors, and putting them in 8 pin blocks that I got from mainframecustom.

The only pin out I've been able to find says pins 1,2,3 are +12v, the rest are ground. I have no idea what psu that pinout was for, it's just printed in the PCIe section on one of the cable modding websites.

I could open my pc and use a multimeter to check the voltage from each pin, but I was hoping someone would have encountered something similar before, and have some quick advice on how to make the 6 pin cable.

Should I just use pins 1,2,3 + 5,6,7 and leave pins 4+8 absent on the PSU side when I make the 6 pin cable?
 

johnrob

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Nov 22, 2014
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Theoretically if you are using a 6+2 cable and you the cables from the psu run straight from pins 4 and 8 to the +2 connector on the gpu side, then you could just leave those out.

I just want to make sure that's an okay thing for me to do.
 

Darkbreeze

Retired Mod
The only pin out I've been able to find says pins 1,2,3 are +12v, the rest are ground. I have no idea what psu that pinout was for, it's just printed in the PCIe section on one of the cable modding websites.
And herein lies your problem, because the pinouts can vary from PSU to PSU and even model to model sometimes within the same series, or within a different VERSION of the same series, going from an older to a newer version for example. You need to KNOW exactly what is what, or you will stand a good chance of frying something. If you created these cables yourself, you SHOULD probably still have at least one extra PCIe 6+2 cable that didn't get modified that came with the PSU, that you can look at the wires and determine what needs to be used and what doesn't, thereby creating your own pinout guide.
 

johnrob

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Nov 22, 2014
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Don't understand why everyone here is so condescending.

If you can't post a helpful reply then don't reply, pretty easy.

I made these cables more than a year ago, I don't have the pinout diagrams, and I used both included PCIe cables to create the two that I have in my system now. I am pretty sure I remember these being straight p1 to p1, p2 to p2, etc... cables, but I was hoping someone would be able to point me to where I could find an actual pinout for my power supply without me having to open up my case, remove the cables, and trace them myself.
 

Darkbreeze

Retired Mod
https://www.overclock.net/forum/18082-builds-logs-case-mods/1420796-repository-power-supply-pin-outs.html

Honestly, took less than a minute to find. It's really not a matter of being condescending. It's a matter of not wanting the average person, who would NOT have been capable of successfully creating their own 8 pin cable without some kind of catastrophe happening, from wreaking havoc on their systems AND probably also a smattering of burnout on people who can't be bothered to look the information up themselves when it is readily available to anybody that looks for it.

In this case, you were probably right to ask, but I think if you could make those cables yourself you should be able to reverse the process yourself as well and I hope you are successful in your attempt.
 

USAFRet

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It wasn't a case of being condescending...rather that we out here were operating on very incomplete information.
Not until much much later was it revealed that you had built this 8 pin thing yourself.
 

johnrob

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Nov 22, 2014
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Just wanted to check back in to let everyone here know that you all were rude, judgemental, and mostly unhelpful. Pretty disappointed coming to a bunch of tech enthusiasts in a PSU specific forum and being told several times that I was wrong and that I should just buy new cables without being provided a solid answer until I proved that my functional, custom cables were in fact as I described in the first place.

In my case I can simply ditch pins 4+8 on the PSU side and swap out the (one piece) 6+2 connector I have for a 6 pin PCIe connector using pins 1-3 and 5-7.

I also understand that the PCIe pinout is not the same for every manufacturer for whatever reason even though every video card wants +12v on pins 1-3 and ground connections on the rest of the pins. Also, that if you plan on doing something similar please make your own pinout based on your OEM PSU cables because if you come to an internet forum of supposed experts for help you will be first ridiculed and demeaned.

With all the gate keeping trolls around "information age" is woefully inaccurate.
 

Darkbreeze

Retired Mod
You know, that sounds almost exactly the same as what practically every person who ever came here and was unwilling to put in ANY work in order to solve their own problems has also said. Amazing how that works. I'm sure this thread would have turned out much different if:

1. You wouldn't have practically started the thread by insulting people who originally were trying to help you by calling them obtuse

2. You could have been bothered to spend five minutes looking at your system, since you clearly felt there was no need for YOU to put in work in based on this comment:

I was hoping someone would be able to point me to where I could find an actual pinout for my power supply without me having to open up my case, remove the cables, and trace them myself.
So then I DID provide a link to you, to the only pinout repository I am aware of, and you come back here and say this?:

Just wanted to check back in to let everyone here know that you all were rude, judgemental, and mostly unhelpful.
3. Had you, from the start, made it CLEAR that you had made your OWN custom cables into an 8 pin from the 6+2 pin that they originally were, almost this entire thread could have been about nothing more than the link I gave you towards the end.

But regardless of all that, thanks for stopping by. Maybe you'll be a bit clearer, and have better luck, on the next go around. If there is one. At least you got it sorted out, it seems, so good luck to you.
 
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