[SOLVED] Can i power this GPU with a split PCie cable?

[Mariusglock]

Hi there forum.

I was wandering, could i power my GPU with a split PCIe cable, or should i rather, connect 2 seperate cables for both slots.

Should i get any disatvanages with the current PSU if its powered with the 1 split cable?

This is how it is connected now, with the split cable (original cable from PSU):

https://imgur.com/a/DcxRWak

Here are the full specs for power consumption purposes:


PCPartPicker Part List

CPU: Intel Core i5-12600K 3.7 GHz 10-Core Processor (€312.95 @ Megekko)
CPU Cooler: Noctua NH-D15 chromax.black 82.52 CFM CPU Cooler (€99.00 @ Amazon Netherlands)
Motherboard: Asus PRIME Z690-P D4 ATX LGA1700 Motherboard (€252.95 @ Megekko)
Memory: Corsair Vengeance LPX 32 GB (2 x 16 GB) DDR4-3200 CL16 Memory (€104.90 @ Amazon Netherlands)
Storage: Kingston HyperX Fury 240 GB 2.5" Solid State Drive
Storage: Kingston A400 240 GB M.2-2280 Solid State Drive (€32.99 @ Amazon Netherlands)
Storage: Seagate BarraCuda 1 TB 3.5" 7200RPM Internal Hard Drive (€37.99 @ Amazon Netherlands)
Video Card: Gigabyte GeForce RTX 3060 Ti 8 GB GAMING OC PRO Video Card
Case: Azza Storm 6000-RGB ATX Full Tower Case
Power Supply: Corsair RMx (2021) 850 W 80+ Gold Certified Fully Modular ATX Power Supply (€144.90 @ Amazon Netherlands)
Total: €985.68
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2021-12-25 18:29 CET+0100

 

[hotaru.hino]

The only disadvantage of using a split cable as far as I know is the voltage drops slightly (but still within tolerance) when you're pushing the video card. However this is only really a problem if you're trying to overclock the snot out of the thing.

I've been using a single cable with my 2070 Super for a while, there hasn't been any problems with it.

EDIT: Since this is the selected answer, I feel I should add some more detail in case someone stumbles upon it.

There was a performance test done between using a single cable and two cables, but again, the performance improvement is slight (i.e., probably only matters in benchmarks)

Also note that towards the end of the video, they said a proper to-spec PCIe 8-pin cable can support up to 396W of power. I think the voltage thing was a fluke of memory, but lots of power sources will drop in nominal output voltage the more current you ask from it.

 

[DRagor]

Does not matter. You have very good PSU and it can handle it no matter if you use single split cable or two separate cables.

 

[Math Geek]

as said above, that old myth was based on some real junk units people insist on buying still.

but a quality unit like yours is designed to handle the power draw and will have no problem supplying the power from a single cable. don't clutter up your case with multiple cables when you don't need to

 

[Mariusglock]

Thanks for the answer guys, I will leave the one cable like it is

 

[SkyNetRising]

The only disadvantage of using a split cable as far as I know is the voltage drops slightly

It has nothing to do with voltage drop.
It has everything to do with heating up the cable.
With smaller cable diameter more heat gets applied to the cable. Sometimes it can melt cable or connectors or even cause fire.
When you're using 2 cables instead of one, you essentially are using larger diameter cable.

 

[Mariusglock]

It has nothing to do with voltage drop.
It has everything to do with heating up the cable.
With smaller cable diameter more heat gets applied to the cable. Sometimes it can melt cable or connectors or even cause fire.
When you're using 2 cables instead of one, you essentially are using larger diameter cable.

Thansk for the reply.

Did not know that it could heat up.
Why would my PSU come with a split cable for gpu, shouldnt it be rated to withstand heavy loads in that case?

 

[DRagor]

Well, there are PSU manufacturers that name their units 700W while in reality they can barely deliver 500W. And there are manufacturers that include split PCIe cables that are too thin to reliably work under full 300W load. But RMx is one of the best units and if Corsair included split cable they made sure it is capable of delivering full load to both connectors at same time.

 

[Math Geek]

yes it should and quality units are designed correctly to withstand the power going through it.

it's those "1000w" junk units you can find for $30 that do not use the correct pieces to prevent such issues. that is where the idea comes from since even some mid-grade units from some usually quality brands have done the same thing.

but when you are working with the better psu's available, such as yours, they are made correctly and do not pose such a threat.

 

[hotaru.hino]

It has nothing to do with voltage drop.
It has everything to do with heating up the cable.
With smaller cable diameter more heat gets applied to the cable. Sometimes it can melt cable or connectors or even cause fire.
When you're using 2 cables instead of one, you essentially are using larger diameter cable.

Then that's a junk quality cable. Any PSU manufacturer worth their salt would package a cable that could carry the current.

I mean it's a fair statement to make, but I'm sure Corsair wouldn't be providing splitters on their RMx series if it wasn't safe as in my configuration.

 

[Mariusglock]

Thank you for your replyes.
According to you guys, and i searched around the internet aswell, it seems that this model of PSU is more than capable to run the GPU with the 1 split cable, altho it does improve performace very slightly (@hotaru.hino) (1-5fps when gaming) when running 2 seperate cables on high performance tasks.

 

[InvalidError]

It has nothing to do with voltage drop.
It has everything to do with heating up the cable.

Which is only a problem with poorly made cables. Most molten connectors are on daisy-chained cables and I bet the main reason for it is over/under-crimping.

As far as copper wiring in a wiring cabinet is concerned, #18 wires are fine to use at 10A. Properly made and crimped MiniFitJr pins can carry up to 13A each in their high-current incarnation, so a state-of-the-art #18 6-pin PCIe AUX cable and connector would be perfectly safe up to 30A, which is 480W at 12V.

That the PCI-SIG down-rated the spec to 6-75W/8-150W shows how little faith it had that PSU manufacturers would come remotely close to doing the right thing there.

The SIG's confidence with MiniFitJr connectors appears to have gone up a lot though with the 600W 12-pins PCIe5 AUX connector allowing 4X as much power over 1.5X as many pins, 2.66X as much current per pin but still less than half of what it could be.