Corsair doesn't kid around when it makes power supplies. Though it does have the odd model that any random consumer can get, most of its PSUs are for the upper mainstream and high-end markets.
The 860-Watt AX860i and AX860, as well as the 760-Watt AX760i and AX760, are definitely high-tier products.
The “i” models are mostly identical to their respective siblings, except for one thing: they are designed with digital signal processors (DSP), which regulate power input and output, making sure a PC motherboard and other hardware always get exactly how much energy they need.
A USB 2.0/1.1 connector links the DPS and monitoring chips with the motherboard, enabling the system to use the Corsair Link software (included in the package).
All four PSUs have six PCI Express 6+2-pin power connectors (each) and other cables that can be put in or taken out at any given time (a modular design). The prices are of $249.99, $219.99, $229.99, and $199.99 (AX860i, AX860, AX760i, and AX760), and just as many Euro in Europe.