The big picture: Since the announcement of Nvidia's RTX 40-series graphics cards, some consumers have been curious or even worried about their power supply, wondering if it can safely run a new GPU. Thankfully, Nvidia has cleared the air and reassured users regarding the power requirements for its cards.
When Nvidia announced its upcoming RTX 40 series graphics cards, it confirmed that every Ada Lovelace card would use the new ATX 3.0 compliant 12VHPWR cable. This cable can supply up to 600W, which is 4x the wattage of a traditional 8-pin PCIe cable. It also has four "data" pins, which allow the power supply to communicate directly with a GPU.
Nvidia revealed power draws for each of the three graphics cards. The RTX 4090 has a TDP of 450W, the RTX 4080 16 GB draws 320W, and the RTX 4080 12 GB pulls up to 285W. It recommends power supply wattages of 850W, 750W, and 700W for each of the three GPUs. However, the company says the new graphics cards will still work with ATX 2.0 power supplies.
Manufacturers will include an adapter with either three 8-pins or four 8-pins to a single 12VHPWR cable, allowing consumers to use the GPUs on older power supplies. However, PCI-SIG believes these adapters could potentially cause issues for some users.
A report from PCI-SIG warned of potential over-current and over-power risks with the adapters. An Nvidia FAQ rebutted the warning saying that while the concerns are legitimate, the adapters should not affect its new cards. The company claims that these were simply a "potential issue with a prototype connector" that it fixed before the official launch of the graphics cards.
The bottom line is as long as the power supply meets the GPU's wattage requirements, there is no reason to worry about using an ATX 2.0 power supply adapter with the latest graphics cards. Nvidia has fixed them so that they won't have a meltdown. However, those who upgrade to an ATX 3.0 power supply should use the 12VHPWR cable to get all the benefits, including GPU communication through the data pins.