[SOLVED] Best 3x8 Pin PCIE Cable Layout

[lNexu]

I'm planning on upgrading to a 3090 - likely the ASUS ROG Strix variant. This has a 3 x 8 Pin power connection layout and is expected to pull 400w.


I upgraded to a 1000w PSU to prepare for the new card, but I'm curious what would be the best layout of connecting the card to the new power supply.

I seen a video by JayzTwoCents where he tried a single cable that had a split from the GPU to the psu vs 2 separate direct cables from GPU to PSU and there was a slight increase in performance, I was curious what would be the best cable layout for this three 8-pin GPU?

Thank you,

 

[siaan312]

Each cable can do 150 watts, and the slot can do around 75 watts.
Say the cable that splits from 8 pins on the psu to 2x8 is not fully 300 watts, Even if it was lets say, 2/3rds efficent, meaning 200 watts from that, the other straight 8 pin from psu should give you another 150 watts (since it's not split, we can expect the full 150 watts)
then another 50 or so watts from the pcie slot.
That's 400, with even more extra left over.

So a double 8 pin, then a single 8 pin should be more than enough.

 

[jay32267]

I'm planning on upgrading to a 3090 - likely the ASUS ROG Strix variant. This has a 3 x 8 Pin power connection layout and is expected to pull 400w.


I upgraded to a 1000w PSU to prepare for the new card, but I'm curious what would be the best layout of connecting the card to the new power supply.

I seen a video by JayzTwoCents where he tried a single cable that had a split from the GPU to the psu vs 2 separate direct cables from GPU to PSU and there was a slight increase in performance, I was curious what would be the best cable layout for this three 8-pin GPU?

Thank you,

Basically you want as much cross sectional copper as you can get between the PSU and the card.

The more conductors the better.

Splitting will result in lower voltages at both ports on the card (not good) as opposed to if you ran two separate cable groups directly from the PSU.

 

[lNexu]

Each cable can do 150 watts, and the slot can do around 75 watts.
Say the cable that splits from 8 pins on the psu to 2x8 is not fully 300 watts, Even if it was lets say, 2/3rds efficent, meaning 200 watts from that, the other straight 8 pin from psu should give you another 150 watts (since it's not split, we can expect the full 150 watts)
then another 50 or so watts from the pcie slot.
That's 400, with even more extra left over.

So a double 8 pin, then a single 8 pin should be more than enough.

Awesome, so as much as I would prefer a single 8 pin PCIE cable, I haven't been able to find any thus far;

Would 2 2x8 cables work as effeciently if I just left the 4th connector from the cable hanging off to the side?

 

[siaan312]

Awesome, so as much as I would prefer a single 8 pin PCIE cable, I haven't been able to find any thus far;

Would 2 2x8 cables work as effeciently if I just left the 4th connector from the cable hanging off to the side?

Yes, but you should be able to obtain a single 8 pin.
Maybe cablemod or similar.

 

[lNexu]

Yes, but you should be able to obtain a single 8 pin.
Maybe cablemod or similar.

All that I was able to find was this page from CableMod: https://cablemod.com/product-category/cable-extensions/8-pin-pcie/

But these just seem to be short length cable extensions. I suppose for aesthetics I can use 3 of these extensions going into 2 2x8 cables out of sight but Idk if that would limit the power after all those connectors, etc.


Sidebar: I stumbled across a video saying that PCIE 3.0 may bottleneck my GPU in heavy scenerios. I may make a separate post regarding this but what are your thoughts? I just got a Z390 Auros Pro Wifi for my CPU and really don't want to upgrade so soon.

 

[siaan312]

All that I was able to find was this page from CableMod: https://cablemod.com/product-category/cable-extensions/8-pin-pcie/

But these just seem to be short length cable extensions. I suppose for aesthetics I can use 3 of these extensions going into 2 2x8 cables out of sight but Idk if that would limit the power after all those connectors, etc.


Sidebar: I stumbled across a video saying that PCIE 3.0 may bottleneck my GPU in heavy scenerios. I may make a separate post regarding this but what are your thoughts? I just got a Z390 Auros Pro Wifi for my CPU and really don't want to upgrade so soon.

That's a hard question.
We don't have any way to test it until the 3090 and 3080 launch, since there are no high end pcie gen 4 cards.
Maybe the Raedon VII, and that card is so dead no one would have cared to test it.

I believe that it would not be a bottleneck.
since even gen 2.0 16x is barely a bottleneck for a 2080 ti.