RTX 3080 power connection from a single PSU cable

[CodeThief]

Hi all,

If I ever actually manage to get a 3080 I'll need to plug it into something. I recently received an Antec High Current Gamer 750w PSU and was wondering about the current capability of a single cable. The 8 pin PCIe cables for this PSU have 2 connectors rather than one, with one daisy-chained off of the other.

Assuming worst case of 350w of power at 12v that's around 30A of current. Does anyone know if a single cable will be suitable for that current draw? I'd rather not have to snake 2 cables from my PSU to the GPU if possible, but then I also don't want a smoking mess of melted plastic and copper!

Thanks

 

[Pablo010]

Every outlet and seller is saying you need to use 2 x 8-pin cables, I really wouldn't risk damaging a new graphics card just to save having to route an extra cable

 

[opethdisciple]

I believe you must have two separate cables. Two plugs from one cable will not do the job.

 

[Digital X]

Seasonic had an infopgrahic showing you will need two seperate cables from the PSU into the GPU, and not to daisy chain the Y looking cables. If I find it I will edit it in.

 

[CodeThief]

Nice one, thanks all. I'm certainly not going to risk damaging anything - hence the question!

 

[Digital X]

OK I found one infographic, not Seasonics but holds true https://www.game-debate.com/blog/images/_id1599566843_1406098.jpg

 

[CodeThief]

Good stuff, thank you

 

[Digital X]

You're welcome.

 

[alec]

Yea, for 200W class cards I'd feel fine using one cable
3080 is confirmed 300-350W, like you said, easiest way to get melted plastic

 

[BallistixOnZ490]

PSU manufacturers / Cablemod should be making 2xVGA output to 1x12 pin connectors for their modular PSUs, I've heard that EVGA have already started doing this and will send you such a cable if you email them, except I dont have a 3080 yet to need to ask for one. If you cant get one from your PSU manufacturer or somewhere reputable like cablemod, then just use the included adapter.

I wouldn't risk getting some offbrand cheap converter as Nvidia already state using third party connectors will void the warranty, so stick to sending a support email to get an official one for whichever PSU you have.

Most definitely do not use any such 1x8 pin to 1x12 pin if they start to crop up, the 12 pin cable needs 2x8 pin inputs.

 

[passey89]

Technically you should be able to run off 1 cable that splits to 2 x 8 as long as it came from the manufacturer like that.

From internet
The pci-e 6 pin connector has 3 pairs of wires, each carrying 12v to the video card. This means that in theory, a device could take up to 3 pairs x 9A (contacts inside connector limitation) x 12v = 324 watts of power. The pci-e standard limits this connector to 75w for safety and redundancy (for example, what if it's a cheap power supply with poor quality contacts, or what if one pair of wires makes poor contact inside the connector and basically carries no current, leaving the two other pairs do the heavy stuff ?)



The pci-e 8 pin connector still has only 3 pairs of wires, but adds two more wires which are connected to ground, and these only tell the video card that it's allowed to take up to 150 watts through the cable. The actual power is still only carried through the 3 original pairs of wires. Originally, one of the wires was supposed to be to allow the power supply to sense the voltage drop on the cables and counteract such voltage drops by increasing the voltage, but no power supply actually does that (as it would have been expensive)

 

[Armageus]

Assuming worst case of 350w of power at 12v that's around 30A of current. Does anyone know if a single cable will be suitable for that current draw?

Depends on the gauge of the cable - if you can confirm it's actually 16AWG, then it should be fine, anything less (i.e. bigger numbers 18AWG, 20AWG) then definite nope.

https://www.tomshardware.com/uk/reviews/graphics-card-power-supply-balance,3979-6.html

 

[passey89]

Seasonic use 18AWG just asked them.

The cables used are 18AWG but even if they were using 16AWG, we recommend to use 2 PCIe cables when consumption under load is > 225W. With 3080, its clearly needed. The weak point is the connector and not really the wire itself:

 

[stevewick]

Hi all can I just confirm this is ok I have connected my evga 3080 with a daisy chain of 2 x6+2 pcie and a connector for 2 ide into 1 8 pin pcie from a 850 watt unit.

 

[pp111]

Use two!

 

[stevewick]

Sorry it’s the evga 3080 ftw3 and needs 3 inputs .

 

[RobinGopher]

In your case the weakest link is the "IDE" molex -> 8pin because those cables were specced to run a hard drive or 3 and are also often jank. However 3x8pins is pretty ridiculous so it might all balance out in the end. You could load it up with a benchmark and then hold the cables see if they are getting warm...

 

[Guest2]

Old thread i know but better than creating another.
EVGA 850w g2 PSU here. I currently have one 6+2 and one 6 going into a GPU.
When moving to an FE card, could I not use the two individual 6 pin VGA power cables from the PSU? These are not on the same cable, individual 2 x 6 pin on 2 cables

If i’m reading correct, the 6 pin individidual modular cables should not be used as don’t carry enough current, hence the included adapter is is the only way to connect requiring two 8 pins connectors...

Or one of the new 12 pin aftermarket modular cables. Do Nvidia not make some 12 pin cables themself, instead of using the terrible looking splitter?