If you haven’t seen a computer power supply, they’re easy to locate. In the case of a computer, generally on the bottom or top, there will be a rectangular cube. One end of this, the outer side, will hook up to the wall power. The other end will have multiple power outlets hanging off of it. They oftentimes have a separate power switch than the computer itself, usually located on the back of the machine. Most of them have outlet cords that can be detached from the power supply, the cords having a female adapter and the power supply having prongs that plug into it.
The computer power supply functions as a very sophisticated device in its own right. It can take the wall voltage and step it down to several different voltages. Not only do these voltages have to be available, they have to be consistent. This means that the power supply has to provide some protection against unexpected spikes in the power that it distributes to the motherboard and other components.
Computer powers supplies will usually have 3.3v, 5v and 12v connectors on them. They will have various pin configurations on the connectors. These pin configurations prevent the power supply from being plugged into the wrong component by accident. For instance, the power supply outlet for the DVD drive will not fit the power supply receptacle on the motherboard, which prevents potential disasters.
There are adapters available that allow some power supply outlets to be combined or converted into other types where the voltages are compatible. Video cards, for instance, oftentimes have specific types of connectors for power—oftentimes to power separate fans—that may require an adapter to be hooked up to some power supplies to accommodate the device. These adapters make it possible to use power supplies that may have become outdated due to changes in hardware.
Your power supply also has some smart aspects to it. The computer can kill the power to the machine and the power supply is capable of receiving signals from the operating system that tell it to shut down. This is why you don’t have to manually turn the power supply button off when you want to shut down your machine.
When your powers supply is off, it’s not actually off. There are still 5v stored in it. This is how the power supply can receive the on signal from the power button on the computer.
Electrically speaking, power supplies aren’t the most complex devices in the world. Their additional functions, however, greatly increase their overall complexity and make them very convenient to use.