The PCIex16 slot on mainboards is specified to supply a maximum Wattage of 75W, so lower end Graphics cards don't need additional power connectors.

What about Graphics Cards that do have one or multiple 6- or 8-pin connectors? Do they still use the power from the slot, or do they rely solely on the power that is supplied directly by the PSU?

The specific card in question is the nVidia GTX 970, which - in the reference design - is specified to have a TDP of 150W, and two 6-pin connectors, which can supply 75W each, so that would be enough for the card.

  • This entirely depends on the card. You should follow the installation instructions and read the product's specification for specific power requirements.
    – Ramhound
    Nov 14, 2014 at 13:19

1 Answer 1


It depends on the card. The card is allowed to draw up to 75 Watt. It does not need to draw as much as it can.

E.g. A card with a 6 pin PCI-e power connector is allowed to draw up to 150 Watt (75 from ther PCI-e connector and 75 Watt from the 6 pins connector). If it only needs 125 Watts then drawing 75 Watt from the 6 pins connector and 50 Watt via the PCI-e slot on the motherboard is fine.

(I would even say 'preferred' since the path between the PSU and the graphics card is probably a lot shorter, leading to less losses and less heat).

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