ATX 3.1 Explained — Why Your Next PSU Should Be Compliant

Intel’s ATX 3.1 standard is now the de facto baseline for new PSU purchases. The reason matters more than the version number suggests.

The headline change is the new 12V-2×6 connector, which replaces the 12VHPWR connector that powered the RTX 4090 generation. The pin geometry is updated, the sense pins are pulled back, and the connector is rated to handle the same 600W power delivery — just safely.

The bigger spec change is transient response. ATX 3.1 PSUs must hold output stability through 200% transient spikes for 100 microseconds — which matches the actual behavior of modern high-TDP GPUs under sudden load. ATX 3.0 (and earlier) PSUs would shut down or output dropouts under those spikes.

Backward compatibility is straightforward. ATX 3.1 PSUs include adapter cables for older 8-pin and 6+2 connectors, and the standard mounting and bracketry have not changed. There is no reason to buy a non-3.1 PSU in 2026 unless you are clearing out a specific deal.