pcie cables confusion

domakun · September 11, 2022

hi so i have the coolermaster masterwatt 650w 80+ bronze, and have been thinking of upgrading to a 3070, which requires 2 6+2pins. i cant seem to find a second pcie cable from the psu though. instead i found out that my single pcie cable has 2 6+2pins connector at the end (see image). does this mean that it would work if i just connect all 18 pins into the gpu? i should probably upgrade to a 750w soon but for now, am i suppose to only have one cable with 2 6+2pin connector heads?

MLConian · September 11, 2022

When I recently built my own pc, my BeQuiet PSU had the same thing - 2 6+2 connectors coming out of 1 PCIe power connector on the PSU side. That cable had more connectors on the PSU side (it's a modular PSU) than the other 6+2 connectors. You should be fine with this connector, it's not as if they just spliced the cables - they probably just have common grounds and the rest is individually wired.

--SID-- · September 11, 2022

Although 650w should be enough for a RTX 3070, the topology of your PSU is not. You don't want to use a double forward topology with such powerdemanding GPU. The PSU should get coilwine and the transformer starts banging because of the high transient response time of double forward PSUs.

What's the wire gauge of the PCI-e cable to the first connector?

And there's a white extension between the PCI-e cable and the GPU?

When you use one PCI-e connector, always use the first connector on the PCI-e cable!

MLConian · September 12, 2022

On 9/11/2022 at 9:25 AM, --SID-- said:

And there's a white extension between the PCI-e cable and the GPU?

That's a Cooler Master PCIe extension cable.

This PSU should be good enough to run an RTX 3070. It's a semi-modular design, so there should be a second PCIe cable to plug into the PSU. I'd advise you to use that, instead of piggy-backing on this connector now that I've done my research on it. If you don't have that cable anymore, I'd contact Cooler Master to see if they could sell you one - alternatively, get a different PSU. This 6+2 pin connector is definitely not the same as the one I have on my PSU, it's just an 8 pin they split into 2 6+2 pin connectors.