One cable with two 8 pin connectors (6+2) or two cables with 1 Connector?

[Spiretec]

So i just got the MSI 2080 gaming x trio and it needs 2 x 8 pin to powerup.

 

Now all of my psu's (corsair rm1000x) pcie cables are 2 x 6+2.

So i can fill both of the slots with just 1 cable... But should i?

 

Or should i use 2 cables? (since every cable is 2 x 6+2 i would then be having 2 x 8 pins just hanging. Now i don't mind the aesthetics but adding more cable in this case is tedious)

 

Thank you

[Jurrunio]

you can do it. In theory using two cables is electrically better, but it makes no difference in reality.

[Spiretec]

7 minutes ago, Jurrunio said:

you can do it. In theory using two cables is electrically better, but it makes no difference in reality.

The thing that had me wondering was that literally all the pcie cables are the same ( 16 pins total, 1 cable having 2 x 6+2) So i was wondering if they want me to use just 1 cable for a 16 pin gpu or something...

[mariushm]

Through both the pci-e 6 pin connector, or the pci-e 8 pin (or 6+2), power is sent to the video card through three pairs of wires.

Each pair of wires can transfer up to 9A of current, or 12v x 9 = ~ 110 watts , so in total up to 300 watts can be sent through each connector.

For safety reasons and for other reasons, the organization that made the pci-e standard set the rules that a video card may not take more than 75 watts through a 6pin connector, and more than 150 watts through a 8 pin connector.

So because of this, it's possible to put two connectors on one cable coming from the power supply, because the pairs of wires and the connector on the power supply side (if any) can handle 300 watts.

The reason they're not going with 4 separate long cables from the power supply is to save money (because the wires cost money) and because there may not be room on the back of the power supply for additional connectors (in case of a modular power supply)

 

The two connectors per cable make sense with cards that don't use a lot of power, like let's say two GTX 1070 in SLI.

Each GTX 1070 consumes up to 150 watts, with around 40-50 watts taken from the pci-e x16 slot and 100-110 watts from the pci-e 8 pin connector, so a single cable with two connectors would handle just fine around 200 watts added up. There's no need to add a second cable unless you want to.

If you have a power hungry card that consumes more than let's say 200 watts, then using two separate cables with connectors can help.

[Mick Naughty]

I do both. Mainly because that’s how my psu’s are. One only has single 6/8 pins. 

The other only has dual. Results are the same. One just looks better depending on the hardware used. 

[Kalm_Traveler]

2 hours ago, Jurrunio said:

you can do it. In theory using two cables is electrically better, but it makes no difference in reality.

It does actually improve performance in reality, just a little bit. 

 

My own experience has shown that it helps with stability when overclocking near the top of where the card can handle.

 

 

[Jurrunio]

3 hours ago, mariushm said:

The two connectors per cable make sense with cards that don't use a lot of power, like let's say two GTX 1070 in SLI.

Each GTX 1070 consumes up to 150 watts, with around 40-50 watts taken from the pci-e x16 slot and 100-110 watts from the pci-e 8 pin connector, so a single cable with two connectors would handle just fine around 200 watts added up. There's no need to add a second cable unless you want to.

If you have a power hungry card that consumes more than let's say 200 watts, then using two separate cables with connectors can help.

^^ exception will be cards like the R9 295X2. It might only have 2 8pin connector, but drawing 400W+ is easy. On custom liquid cooling even 500w is achievable.Two separate cables are a must for these cards.

[Mister Woof]

Depends; i have read stories of Vega 64's with a double 8 single cable having issues and requiring using individual 8s.

 

I am using individual 8s because i didn't want to chance it. And because the PSU came with 2 anyway.

[Ice_Wallow_Dee]

I'm sorry to post this old thread but it's only in this forum i can find. 

 

I have 5700 XT card and i'm installing it tomorrow. Should i use one cable with 2x6+2 pins or should i use two separate cables with 2x6+2 pins? 

 

Im asking this because of the cable management reasons

[mariushm]

It doesn't matter.

In theory, using more wires between power supply and video card (so two separate chains, and using one connector from each chain) would be a bit better.

That card averages 220 watts, and peaks at around 250 watts for very brief moments (milliseconds).  A single chain of connectors is good for up to around 400 watts, so it won't be an issue if you use both connectors from a single chain of connectors.

[PauloFeitosa]

On 5/5/2020 at 6:31 PM, mariushm said:

It doesn't matter.

In theory, using more wires between power supply and video card (so two separate chains, and using one connector from each chain) would be a bit better.

That card averages 220 watts, and peaks at around 250 watts for very brief moments (milliseconds).  A single chain of connectors is good for up to around 400 watts, so it won't be an issue if you use both connectors from a single chain of connectors.

I would like to complement that if you're intending to use your system for data mining or applications that use 100% GPU for extended periods of time, consider using two cables to keep the temperature lower at the PSU connectors. Also, the better the PSU's yield (check it's 80 plus certificate), the less heat in the cables.

[Mark Kaine]

18 minutes ago, PauloFeitosa said:

I would like to complement that if you're intending to use your system for data mining or applications that use 100% GPU for extended periods of time, consider using two cables to keep the temperature lower at the PSU connectors. Also, the better the PSU's yield (check it's 80 plus certificate), the less heat in the cables.

 

 

info in this thread is outdated, although it still holds true for 2000 / 1000 series cards, but it was never really recommended to daisy chain pcie power cables. 

 

 

[Ahmed Shah]

On 1/24/2021 at 3:36 PM, Mark Kaine said:

 

 

info in this thread is outdated, although it still holds true for 2000 / 1000 series cards, but it was never really recommended to daisy chain pcie power cables. 

 

 

So bottom line is anything above a 3060 should use two pcie cables and not one pigtailed?

[Ar558a]

Always use two cables for safety not worth the fire risk.