Will a 6+6pin PSU work with a GPU that has a 8+6 pin connection?

Xolin · October 24, 2020

Will a 6+6pin PSU work with a GPU that has a 8+6 pin connection or will I need to buy a new PSU?

GPU: Nitro RX 570

PSU: Thermaltake 550W

mariushm · October 24, 2020

In general it depends on the quality of the psu and how much current it can supply on the 12v outputs. The amount of current is written on the label of the psu.

The connectors are irrelevant, you can use 2 x molex => pci-e 6 pin / 6+2 pin / 8 pin adapter cables or 2 x sata => pci-e 6/6+2/8 pin adapter cables to get a card working even on a psu that has no pci-e connectors.

The 6 pin connector simply means the video card is allowed to take "up to" 75 watts from the psu.

The 8 pin connector simply means the video card is allowed to take "up to" 150 watts from the psu.

In the case of the RX 570, the video card will average around 180 watts - the video card is allowed to take up to around 65 watts from the pci-e slot itself, and the it can take up to 150 watts from a single pci-e 8 pin slot ... and the video card manufacturer could have stopped there, because 65 watts + 150 watts = ~ 215 watts, which is more than 180 watts.

In your particular case the manufacturer probably thought... let's add a 6 pin connector to give the video card the ability to take up to 75 watts more, just in case the user wants to overclock the video card, but also so that the video card doesn't have to take so much energy from the pci-e slot (because that energy comes from the 24 pin atx connector, and there's only two 12v wires in it, so it's not optimal)

If you psu has two 6 pin connectors, that means for various reasons they're confident they can supply up to 2 x 75 watts to a video card through those connectors. Doesn't say anything about what you can do with the rest of the energy, all the way to the total available on the 12v output of your power supply. From those 550 watts, your power supply probably supplies around 400-430 watts on 12v.

It could marketing decision, it may have had 2 8 pin connectors, but to make you buy the 600-650w models, they only put pci-e 8 pin connectors on those higher end models..

They're also confident they can supply up to around 50-60 watts through each molex (old style hdd connector) - each molex connector is rated for 5A (x12v = 60w)