Corsair Link
A unique feature is the ability to connect the PSU to the Corsair Link system. With an included module you can connect the Corsair AX1200i to an internal USB 2.0 port on the motherboard. The Corsair Link software then lets you monitor various components of the power supply, including the voltage on the different rails, the energy consumption of each cable, the total usage, the efficiency, the temperature, the fan speed, and so on. The fan speed can also be regulated with the software. You can create a profile for the fan, based on the temperatures of the PSU, the CPU, the graphics card and other variables. If you have Corsair water cooling or Corsair Dominator RAM modules, you can control those as well with the same software. Under light loads the measurements of usage and efficiency are not always 100 percent accurate, something Corsair also mentions.
The software makes it possible to supply the max amperes on one or more plugs, if needed. This is great for extreme overclockers that like to boost their CPU and/or GPU.
The screenshots below give a clear picture of all the possibilities of the Corsair Link software.

The module for connecting the PSU to USB on the motherboard
Another unique feature is the self test button on the back. When you press it the PSU checks its own health by measuring its exit voltages and other things.
The price is as impressive as the power supply, on average the Corsair AX1200i costs around £250. It's in line with other 80 Plus Platinum power supplies. For the Enermax Platimax 1200W you pay an average of £260, and for the Zalman Platinum 1250W you pay around £240. Corsair does include a 7-year warranty with its power supply.