A rumor has been spreading around the hardware circles that Nvidia's upcoming Ampere graphics cards might use a 12-pin PCIe power connector. Some news outlets are reporting the rumor as fact, while others are treating it as a sham. Our own insider source has confirmed that the connector is indeed real and has been submitted to the PCI-SIG standards body. However, it remains to be seen whether it will pass approval.
The 12-pin PCIe power connector measures 19 x 14 x 8.35mm, give or take 0.30mm. If you want to get an idea of its size, the 12-pin connector should be roughly equivalent of putting two normal 6-pin PCIe power connectors side by side.
According to the submitted technical illustrations, the 12-pin PCIe power connector would come equipped with six 12V pins and six ground pins. Each 12V pin is rated for a maximum of 9A. Therefore, a single 12-pin PCIe power connector can theoretically provide a power input up to 648W, which blows every existing PCIe power connector out of the water.
The 12-pin PCIe power connector is essentially a combination of two 6-pin PCIe power connectors albeit the different pin layout. As a result, power supply vendors can get away with just swapping the cable with its corresponding connector to the new 12-pin PCIe layout. This would allow them to save money since it wouldn't consist in touching the power supply's PCB.
The wire gauge will play a significant role in power delivery. While the pins on the connector support 648W, you'll need 16AWG cables to get there. This shouldn't be a problem since we don't expect Ampere to draw that much power. The majority of modern power supplies employ 18AWG cables, which have a maximum ampacity of 7A. Even with 18AWG cables, the 12-pin PCI power connector can supply up to 504W of power and should be more than enough for any graphics card.
Ampere graphics cards are rumored to pull up to 350W, which could explain Nvidia's insistence on a new PCIe power connector. Even with the current PCIe power connectors, it's possible to feed a graphics card more than 350W. The PCIe slot provides 75W and a single 8-pin PCIe power connector delivers up to 150W. So a combination of the PCIe slot with two 8-pin PCIe power connectors is good for 375W. If required, you could also add another 6-pin or 8-pin PCIe power connector to the mix. High-end graphics cards, such as the MSI GeForce RTX 2080 Ti Lightning Z or EVGA GeForce RTX 2080 Ti K|NGP|N depend on three 8-pin PCIe power connectors, so it's not uncommon to find graphics card with three power connectors.
Perhaps it isn't a matter of whether current offerings can provide enough power for Ampere – it more likely comes down to marketing. Having multiple PCIe power connectors can give a bad first impression that the graphics card is a power-hungry one. To the untrained eye, a graphics card with a single PCIe power connector infuses an illusion of its power efficiency.
At the moment, it's uncertain if the 12-pin PCIe power connector will be exclusive to Nvidia's Founders Edition models or the same for all aftermarket models. At any rate, we shouldn't be despair since the PCI-SIG group might not even approve the 12-pin PCIe power connector.