Firstly, the main difference is in power delivery and efficiency. ATX 3.0 PSUs offer improved power stability and higher efficiency compared to ATX 2.0 PSUs; this is due to the use of 12VHPWR connectors in ATX 3.0 PSUs. Also, the inclusion of a 16-pin 12VHPWR connector ATX 3.0 PSUs has better compatibility with next-gen graphics cards and other high-end components.