Powering a GPU with both a 6 and 8 pin slot

Hello All and thanks in advance for helping. 
I recently bought a FATBOY XFX RX590 8GB GPU for my personal build. My power source is a 700W (Cooler Master RS-700-AMBA-D3), but it only has 4pin floppy and 6pin PCI-E slots. I have a PCI express cable that has a 6 and 8 pin connector, but I am fairly certain I cannot plug that in solely, right. I would rather not do anything untoward to my machine as I really want to get back to gaming. 
Do you know what kind of cord I should get? Is there a cord or adapter that can connect 4 pin floppy on one end and 6 or 8 pin on the other? Also, I am using a full tower so I will need longer cords 8-12 inch most likely. 
Thanks again, 

Best Answer


  • Ian
    Ian admin
    First Anniversary 5 Insightfuls 5 Likes 5 LOLs
    edited May 2020
    Greetings. Looking up your supply online, on the Cooler Master site http://us.coolermaster.com/product/Detail/powersupply/silent-pro-m/silent-pro-m700.html it says it has 2 6+2 PCI-e adapters.

    You should just be able to plug those into the video card, use one of the 6+2 cables for the 8-pin, and the other for the 6-pin and the leftover 2-pin part on the 2nd PCI cable can just be unplugged and it should be fine to use.

  • Dains_zoo
    We bought our power supply about 10 years ago and I have lost the extra cables to my wife's organization skillz.
    The FatBoy came with a 8-pin to dual female 6-pin cable. I can't tell if that means I need to use 2 6-pin PCIE slots on my power supply to power the 8pin or vice-versa. Either way the cable is too short to reach.What cables do we need to buy? 
  • PowerSpec_MikeW
    PowerSpec_MikeW PowerSpec Engineer
    5 Insightfuls First Anniversary First Comment 5 Awesomes
    edited May 2020
    You can adapt an 6 pin PCIe into an 8 pin. They have the same number of 12v wires, the extra two pins are grounds. Eliminates crosstalk at the higher wattage, the 8 pin allows double the wattage from 75W to 150W. Generally shouldn't be an issue though, unless it's a very long cable with extensions.

    Buy a 6 to 8 pin adapter and just use that one one 6 pin, and the other just connect directly. The alternative is trying to find replacement modular cables, but that's another mess to get into. They're not standard or universal. It varies by the OEM manufacturer of the power supply.
  • Dains_zoo
    I currently have a cable that has a 6-pin that connects to the PSU and goes off into a daisy chain type split. One end of the split is a six pin the other is a 6+2 (8) pin. Could I power my GPU with this one cord?  If so, would that be harmful?
  • Dains_zoo
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