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Use 1 PCIE cable for both GPU ports?

namonami -  
flo88 Posted messages 28530 Registration date   Status Contributor Last intervention   -
Hello! I just finished building my first PC (for 3D work), and everything seems to be working well!
I have a question regarding the PCIe cables:

- My GPU is an MSI RTX 2080 SUPER VENTUS XS OC, and it has 2 ports (one 6-pin, one 8-pin).
- My power supply is a Gigabyte B700H.

The PCIe cables provided with my power supply have 3-4 heads each, which gives me the option to use a single cable for both ports on my GPU. That would be convenient for me, as the inside of my case is starting to get cramped.
Also, I haven't done any overclocking (I prefer not to, as I don't know enough about it).

Will using a single cable instead of two risk creating instability in my configuration, or does it not make a difference? Thank you for your help!

3 answers

  1.
    Aquaran88 Posted messages 160 Status Member 49
     
    Hello,

    Yes, unfortunately, you will need to connect both power cables to your graphics card, otherwise it will be underpowered and won't deliver its maximum performance.

    --
    Aquaran
    2
    1. namonami
       
      Okay, got it!
      Since I don't have much space to run the second cable through the back of the case, is it really a big deal to leave it at the front?
      1
    2. Aquaran88 Posted messages 160 Status Member 49 > namonami
       
      As long as it doesn't disturb another room, no, you can let it go through the front.
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    3. namonami > Aquaran88 Posted messages 160 Status Member
       
      Okay great, thank you for your help!
      0
    4. jumulka Posted messages 12090 Registration date   Status Member Last intervention   4 619 > namonami
       
      in front or behind, it's just a matter of aesthetics
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    5. alalala
       

      Hello, I'm a bit late but I'm asking just in case. I currently have an RX 6750 XT and a Be Quiet 650W power supply that has a single PCIe connector. At first, I powered my graphics card with a single Y PCIe cable, and it worked very well at the beginning. Then, after a week, my graphics card stopped working, and some small red LEDs indicated that the card was poorly powered. I did some research, and it turns out I need two PCIe cables to power it properly, so I got a second Y PCIe cable. Is it serious if there are two cables that won't be connected since they're Y cables?

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  2. epango Posted messages 36739 Registration date   Status Member Last intervention   Ambassador 4 271
     
    Your problem lacks precision. Some power supplies have 2 PCI-E connectors per cable. If that's the case with your power supply, a single cable would be sufficient to power both the PCI-E 8-pin socket and the 6-pin PCI-E socket of your GPU. A second cable would not be necessary.

    --
    Misnaming things adds to the misery of the world (Albert Camus)
    1
    1. flo88 Posted messages 28530 Registration date   Status Contributor Last intervention   5 184
       
      Indeed, it's not clear..... 

      The PCIE cables supplied with my power supply have 3-4 heads each,


      ?? I don't see it, a PCIExpress cable for a graphics card has 6 or 8 pins.
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    2. namonami
       
      Sorry for the lack of clarity, yes my power supply has 3 PCI-E connectors per cable, which indeed allows me to power the 8 pin and 6 pin connectors of my GPU with one cable. But I was just wondering about the stability of the power supply when using one cable with multiple connectors for the two sockets rather than two separate cables for the two sockets.
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    3. flo88 Posted messages 28530 Registration date   Status Contributor Last intervention   5 184 > namonami
       
      Your question is relevant if your power supply has one or two 12V rails; if it has only one rail, connecting two cables will not be useful.
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    4. namonami > flo88 Posted messages 28530 Registration date   Status Contributor Last intervention  
       
      On the box of my power supply, it says "12v single rail," so yes, I imagine it's a single rail. So if I understand correctly, one cable should be enough in the end?
      1
    5. flo88 Posted messages 28530 Registration date   Status Contributor Last intervention   5 184 > namonami
       
      Yes. The presence of a single 12V rail is a guarantee of reliability since almost all of the power is dedicated to it, which is essential for high-performance configurations.
      Using a single cable is not an issue in this case.
      If the power supply had two rails, connecting both allows for the distribution of the load (provided that the two cables are well separated at this level....)
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  3. epango Posted messages 36739 Registration date   Status Member Last intervention   Ambassador 4 271
     
    One must think in basic terms. If it weren't possible, they wouldn't have put 3 connectors on the cable. As for me, I have a GPU with an 8-pin PCI-E and a 6-pin PCI-E, and I use a single cable to power the connections.

    --
    Misnaming things adds to the world's misfortunes (Albert Camus)
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