It works like our heart. Only it distributes correct voltages, not blood, to the different computer components (i.e. motherboard, CPU(s), RAM chips, floppy disks, hard disks, optical disc drives, sound and video cards, etc.) Each of these components has its own voltage requirement.
In order to supply power supply to your computer you would need an outlet plug near your computer. Then you can plug your computer into that and necessarily, use an extension.
When your computer will not power on. When the cooling fan of the power supply has failed. When the amount of hardware in use in your case exceeds the power capability of your power supply.
Use a power supply tester. You can get them on ebay for under $5.
The power supply makes the computer run, without any type of power supply it would be impossible to run a computer. The mains power supply for a laptop and the power supply unit of a desk top, both convert the high AC voltage from the mains power and convert it to low voltage DC, for the electronics of a computer to use.
If it is a computer power supply it is the box that gives the computer its power from the outlet.
The use of computer cases with power supply in them is to be able to charge a person's laptop, netbook, iPad, or other electronic device while it is in the case still.
The Power Supply. It is what you plug the power cord into.
The "power supply" supplies power to a computer. A computer's power supply is a "switchmode power supply" responsible for converting the AC voltage from the wall into several DC output voltages.
The Power Supply. It is what you plug the power cord into.
UPS = Uninterruptible Power Supply
power supply
No FireWire does not need a separate power supply to operate. FireWire is used to connect peripheral devices to a computer.