What is the smallest capacitor needed in a computer power supply in order to produce at least 4.50 v for 0.74 seconds after the power goes off?

What is the smallest capacitor needed in a computer power supply in order to produce at least 4.50 v for 0.74 seconds after the power goes off? assume that the resistance of all the components of the computer motherboard is 6 ohms and that the capacitor and motherboard are powered with a 5-volt power supply?