I recently bought a used RTX 5080 as an upgrade from my RX 6800. I'm planning to use a 1300W Seasonic SSR-1300GD, which is an ATX 2.x power supply. From what I've read, an ATX 2.x PSU can work with the 5080, but I'm unsure how to connect it safely to the GPU's 16-pin power socket.
Should I use the adapter that comes with the graphics card, connecting the PSU's PCIe cables to the adapter and then to the GPU? If the used card does not include its adapter, what type should I buy?
Alternatively, can I connect the GPU directly using separate modular cables, or would it be better to replace the PSU with an ATX 3.x/3.1 model that includes a native 16-pin cable?
2 Answers
The simplest option is to use the adapter supplied with the graphics card. It should connect to three separate PCIe 6+2-pin cables from the PSU, assuming that is the adapter specification for your particular 5080. If the used card does not include one, look for a standard 12VHPWR male-to-3x PCIe 6+2-pin adapter from a reputable manufacturer.
The warning about mixing cables applies to modular PSU cables—the cables that plug directly into the power supply. Those can have different pinouts between brands and models, so only use cables specifically compatible with your Seasonic PSU. Standard GPU power adapters are different and are designed to work with the relevant PCIe cables.
Do not confuse CPU 4+4-pin cables with PCIe 6+2-pin GPU cables. CPU cables should never be connected to the graphics card, since doing so could damage the PSU, GPU, or both.
Replacing the PSU with an ATX 3.1 model that includes a native 12V-2x6 or compatible 16-pin GPU cable is the cleanest and most future-proof approach. However, an appropriately rated ATX 2.x PSU can still work when used with the correct GPU adapter and separate PCIe power cables. A 1300W unit is more than most single-5080 systems need, but extra capacity is not inherently a problem.
That clears things up—I'll use the proper adapter if the seller does not include it. I was referring to the CPU and PCIe connectors incorrectly. Is it possible to use only two PCIe 6+2-pin connectors directly, or does the 5080 specifically require the three connectors used by its adapter?