[SOLVED] Can I use just one PCIe cable for my 8+6 pin Graphics Card?

Jan 23, 2020
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I7 9700K

CORSAIR H100I PRO AIO COOLER

RTX 2070 SUPER (https://www.overclockers.co.uk/gigabyte-geforce-rtx-2070-super-gaming-oc-3x-8192mb-gddr6-pci-express-graphics-card-gx-1b5-gi.html?gclid=Cj0KCQiAnL7yBRD3ARIsAJp_oLZ6CTszfaQ-i2CvCK89QnZ2147rHrEPO9a5VkxQ7MPfVQ_zBHd18yIaAsFREALw_wcB )

(About to order a) Z390 AORUS ULTRA LGA1151

16GB RAM 3200MHZ

CORSAIR RM850 PSU (https://www.corsair.com/uk/en/Categories/Products/Power-Supply-Units/Power-Supply-Units-Advanced/RM-Series™-80-PLUS-Gold-Power-Supplies/p/CP-9020196-UK )

Hi. So I'm in a bit of a predicament right now. I built a computer over a month ago and have been troubleshooting ever since, though this isn't too important for this post.
Basically, I've just returned my Rog Strix Z390-F motherboard and plan on getting a Z390 Aorus Ultra motherboard which needs an additional 4 pin CPU connector on top of the 8 pin. The problem is, I'm using 2 PCIe cables for my GPU so I don't have enough slots on this PSU, and I'm not sure if I can return the PSU at this point (nor do I want to if avoidable) to upgrade to one with many CPU/PCIe slots.

I am wondering if I can use just one PCIe cable ( 2x (6 pin + 2 pin)) for the graphics card, rather than two cables by only utilising the 6+2 pin connector from one cable, and the 6 pin from the other.

Sorry, I hope I've explained it clear enough.
Thanks.
 

MadsModsat

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Your GPU needs power connected to both the 6 and 8 pin socket. Sometimes one cable has two connections for the GPU.
You can use that, but it is usually recommended to use two seperate cables for the GPU.

However, the extra 4-pin for the motherboard is actually optional, it is for extra powerdraw to support power hungry CPUs, which can give better overclock stability, and also provide more power for a second GPU - which means you only need to attach the 8-pin (4+4-pin) for your CPU.
 
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MadsModsat

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Oct 10, 2019
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Your GPU needs power connected to both the 6 and 8 pin socket. Sometimes one cable has two connections for the GPU.
You can use that, but it is usually recommended to use two seperate cables for the GPU.

However, the extra 4-pin for the motherboard is actually optional, it is for extra powerdraw to support power hungry CPUs, which can give better overclock stability, and also provide more power for a second GPU - which means you only need to attach the 8-pin (4+4-pin) for your CPU.
 
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Jan 23, 2020
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All of the yellow arrows can be used for PCI-e and 4+4 cpu plugs You have 5 plugs to use, 2 for GPU and 2 for CPU leaving you 1 extra port open
Thanks for that diagram. For some reason I thought the two in the top middle were a variant of peripheral/SATA cables. Thanks very much for clarifying this. :)
 
Your GPU needs power connected to both the 6 and 8 pin socket. Sometimes one cable has two connections for the GPU.
You can use that, but it is usually recommended to use two seperate cables for the GPU.

However, the extra 4-pin for the motherboard is actually optional, it is for extra powerdraw to support power hungry CPUs, which can give better overclock stability, and also provide more power for a second GPU - which means you only need to attach the 8-pin (4+4-pin) for your CPU.

No where in the manual does it say the 2x2 pin is an optional plug (page 16 of the manual) in fact it actual lables the 2x2 plug first then the 2x4 second. While this was true back with less power hungry cpus intel is moving to 6 and 8 core cpus which is why they no longer state the extra 2x2 plug as an option in the manual anymore.
 

MadsModsat

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What 2x2 plug are you speaking of? I've never heard of a connector of that type on a PSU, and I don't recall metioning anything of that kind in my post

EDIT:
If you are referring to the extra 4-pin, I'm certainly not the only one who postulates that the extra 4-pin isn't necessary, unless you are overclocking - even with an i9 9900K.

Tom's Hardware Forum

Hardforum

Also, both z390 boards I have had, both an MSI MPG Z390 Gaming Pro Carbon and the ASUS Maximus XI Hero (WiFi) actually states that you under NO circumstance must use the 4-pin connector on it's own, but that the 4 pin is optional. 8-pin is required.

Maybe I could have written hat the extra 4-pin is generally considered as being optional, because some manuals are a bit vague in their description of the necessity of the 4-pin connector, but is has been proven several times, that a z390 board and a high end CPU runs fine on just the 8-pin connector.
 
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