I recently bought a used RTX 5080 as an upgrade from an RX 6800. I'm planning to use a 1300W Seasonic SSR-1300GD, which is an ATX 2.x power supply. My main concern is how to connect it correctly to the GPU's 16-pin power socket. Should I use the graphics card's adapter with separate PCIe power cables from the PSU, purchase a replacement adapter if the used card doesn't include one, or replace the PSU with an ATX 3.x model that has a native 16-pin cable? I also want to make sure I don't accidentally use the wrong type of modular cable.
3 Answers
Do not connect CPU 4+4 cables directly to the GPU. The connector types may look similar, but their wiring is different and doing that could damage the PSU or graphics card. The PSU’s modular PCIe cables are the correct source for the adapter. Modular PSU cables themselves must match the exact PSU model, but the GPU’s standard power adapter is not the same thing as replacing a modular PSU cable.
A new ATX 3.1 PSU with a native 12V-2x6 cable is the cleaner long-term option, especially if you’re buying a power supply anyway. However, a quality ATX 2.x unit can still work with an RTX 5080 when using the proper multi-cable adapter. The 1300W capacity is more than most single-GPU systems need, so choosing ATX 3.1 is mainly about newer standards and cable convenience rather than wattage alone.
Use the adapter intended for the graphics card, connecting separate PCIe 6+2-pin cables from the PSU to the adapter and then plugging the adapter into the GPU. If the used card doesn’t include one, buy a standard 12VHPWR-to-PCIe adapter with the number of PCIe inputs specified for your particular RTX 5080. Make sure every connector is fully inserted and avoid sharply bending the 16-pin cable near the plug.
That clears things up—using the GPU adapter sounds better than replacing the entire PSU. I was also mixing up CPU 4+4 cables with PCIe 6+2 cables; I understand now that only the PCIe cables should connect to the graphics card.