Common to all models is a dual 12V rail design. The 500W model uses two 20A rails, the 600W model uses 35A + 25A rails, while the 700W model uses 55A and 25A rails.
The 500W model has sufficient cabling for a performance single graphics card build; the 600W for a mid-range dual-GPU build, while the 700W is fit for a high-end dual-GPU build. Built with Japan-made components, the PSUs use 140 mm temperature-controlled fans, which are designed to be quiet.
Source: TPU