Power supplies must comply with the ATX12V 2.2 design guidelines (see the Form Factors Web site for details) and supply additional current on the 12V power rail through a 2x2 connector or 2x4. The Intel® Core™ i7 processor requires a minimum of 8 Amps continuous and 13 Amps peak for 10ms on 12V2. All Intel® Core™ i7 processor-based systems require either the standard 2x10, 20-pin ATX power connector or the new 24-pin ATX power connecter as well as the 2x2, 4-pin 12V connector. Each motherboard/platform may have additional requirements based on graphics cards, TV tuners, ADD2+, HDD, ODD, chassis fans, etc. Consult the motherboard and system component documentation to determine additional power supply requirements.
The minimum power that you can use would depend on the external components you have plugged into the motherboard. Intel® recommends using a power unit higher than 460 Watts for high ending systems.
You may want to access the following link to check some of the power units that were tested with this type of processors: