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Need help with GPU power cable

ThermalX
Level 10
I bought a EVGA Supernova G2 1000W PSU and I am sleeving the cables, but I ran into a problem. It seems that the 7 pin on the plug that goes into the PSU goes to the 5 pin on the plug that goes into the GPU. Here is a diagram to show what I mean:



And it's the same with other pins on the same cable, even with the MB cable. Although the pins aren't following the 1 to 1, 2 to 2, 3 to 3, etc. order, ground always goes into ground and 12 volt into 12 volt. My question is, can I plug each pin into it's numerically corresponding pin (1 to 1, 2 to 2, etc.) or do I have to follow the psu's original order?

For sleeving purposes, it's obviously nicer to follow numerical correspondence.

I only ask because I read somewhere that some GND pins might serve as a sort of sensor for the PSU. I have no idea if this is true or not.
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5 REPLIES 5

ThermalX
Level 10
Anyone, please? Do I need to put the pins back into the plugs the way they were or can I put them all in parallel?

Melting_Point
Level 10
I'm, not sure about PC PSUs, but many of the high end PSUs that I've worked on did indeed have a sense line. Virtually no current would flow down the sense line, it would simply be used to feed the voltage at the board back into the PSUs feedback circuit. This allowed the PSU to regulate the out voltage at the consumer rather than its own output terminals, and therefore compensate for any voltage drop across the supply cable. Even if PSUs do have sense lines, that wouldn't necessarily mean that you have to wire it back with the same pinouts. If your VGA card also has a sense line inside it (and I have no idea if they do), then you'd need to wire them up the with the correct pinpouts. However, if all the +12V and 0V pins on the connectors of the video card are soldered to gether on the back of the connector, then it wouldn't matter which way you put them in, so long as you didn't swap a +12V lead with a 0V lead.

Having said all that, I'm not sure if this is even the case with your PSU or any PC PSU (But I imagine it would be, otherwise you'd introduce an unstable element via the cable voltage drop) . I had a look online for a schematic for your PSU, but couldn't find one. You could find out for yourself if you've got a multimeter with a sensative enough DC range and something to load the PSU with. Connect up the all the +12V lead to a load resistor (a powerful 12V lamp would be good for this), then measure the voltage drop across each of the wires. If you find one with much less voltage than the rest, then that's the sense lead.

If, after reading all that, you're sitting the scratching your head trying to work out what language I'm speaking in, then you should probably just wire the leads the way you found them, and be done with it. 🙂

Hope that helps.
Motherboard: RIVE (3602 bios)
CPU: Intel 3930K @4646MHz
OS Drive: 2 X Samsung 840 PRO (Raid 0)
Storage Drive: 2 X 1.5TB WD Caviar Black RAID 0, 2 X 3TB WD Caviar Red, Kingston V100 256GB SSD
Memory: 64GB G.SKILL Ripjaws Z (F3-12800CL10Q2-64GBZL)
GPU: Gigabyte GeForce GTX580 @795MHz - 1536MB GDDR5
PSU: OCZ ZX1250
Cooling: Phantek PH-TC14PE
OS: Windows 7 Ultimate x64. (EUFI)

Thank you for your reply! 🙂

I did do some voltage drop measurements on the 12 volt, 3.3v and 5 volt lines, tough I didn't look for the one with the lowest voltage drop. After reading what you said, I suppose it's best I just follow the psu's original order. I only asked because I will be sewing the cables and that gets tough when they aren't all parallel to each other, I guess I will leave the cable crossover right by the psu plug.

Thanks again.

ThermalX wrote:
Thank you for your reply! 🙂

I did do some voltage drop measurements on the 12 volt, 3.3v and 5 volt lines, tough I didn't look for the one with the lowest voltage drop. After reading what you said, I suppose it's best I just follow the psu's original order. I only asked because I will be sewing the cables and that gets tough when they aren't all parallel to each other, I guess I will leave the cable crossover right by the psu plug.

Thanks again.

Probably a wise choice. If the cables was wired less directly than you'd expect, there's probably a very good reason for that.

Once the lid goes on the case, how much difference will it make if your wires aren't perfectly parallel inside the sleeve?
Motherboard: RIVE (3602 bios)
CPU: Intel 3930K @4646MHz
OS Drive: 2 X Samsung 840 PRO (Raid 0)
Storage Drive: 2 X 1.5TB WD Caviar Black RAID 0, 2 X 3TB WD Caviar Red, Kingston V100 256GB SSD
Memory: 64GB G.SKILL Ripjaws Z (F3-12800CL10Q2-64GBZL)
GPU: Gigabyte GeForce GTX580 @795MHz - 1536MB GDDR5
PSU: OCZ ZX1250
Cooling: Phantek PH-TC14PE
OS: Windows 7 Ultimate x64. (EUFI)

Arne_Saknussemm
Level 40
If you open up the PSU and have a look at the back of the modular board you might get a clue....this pic makes it look like the lines are individual and not joined together on the back....

Image

Unless someone comes on here and gives you a 100% answer I would play safe and leave things as you found them...

maybe contact manufacturer?