# The Computer Revolution/Hardware/Power Supply
## Introduction

Power supplies are devices that provide a computer with electricity in a form and quality that it requires to operate. In a desktop computer, this component is often integrated into the computer itself, and is typically where mains power is connected. On laptops this is typically an external brick or wall wart that connects to the laptop. This device converts AC (alternating current) to DC (direct current). This is necessary because computers run on direct current. In this power supply, there is typically an integrated fan to keep it cool, as the conversion results in waste heat. In brief, the power supply takes AC current from the wall, converts it into direct current, and puts it into the motherboard, storage drives, and other devices in the computer that require electricity.

## Power Budget

Wattage is commonly used as a measure of energy that a power supply can deliver to a computer, as well as a unit of consumption for individual parts. Power supplies are often rated with two wattages, peak and continuous. There are other factors that may influence or limit how wattage may be used, such as power supply rails, but for general ballpark estimations using reputable power supplies, this is generally sufficient.
* Continuous Wattage - The maximum wattage a power supply can continuously deliver under normal operation. This is the primary wattage consumers should care about.
* Peak Wattage - The maximum wattage a power supply can deliver for a short amount of time. Peak wattage should only be considered for extraordinary circumstances. By definition peak wattage is always equal to or higher then continuous wattage on a given supply, sometimes by a significant amount. Some less scrupulous manufacturers will advertise a units high peak wattage, while hiding a much lower continuous wattage.
Conversely computer components each have wattage requirements. Every processor, add on card, storage drive, and other device will also have a power consumption rating. By comparing the amount of wattage offered by a power supply, and the total amount of power components are expected to draw, it is possible to figure out if a power supply is sufficient for a system. Typically most components only draw their full rating when in active operation, but it's prudent to ensure everything will be adequately supplied with power when the machine is operating at full capacity.
Any reputable manufacturer or builder will construct computers with power supplies that are suitable for the amount of energy being used by the stock hardware inside of it. At the same time, system builders often save money for themselves and the customer by not shipping power supplies with significantly more capacity then what is required. As a result when upgrading hardware, like a video card or installing new fans, drives, etc. you must first check the required wattage that the particular piece of hardware uses. If your power supply does not meet these requirements you will also have to upgrade to a new power supply to ensure your computer does not crash.
For example, if you have a 400 watt power supply, and you install a new video card that requires 450 watts of energy, you may find your computer crashing when being stressed (watching videos, playing games). If this is the case, do not use the computer until you upgrade your power supply or you remove the piece of hardware that is causing it to exceed it's power rating. This sudden power off of a computer can be detrimental to the internal hardware of the computer.
There are things to protect a computer from electrical problems; they are:
* Surge Protectors
* Voltage Regulators
* and UPS
A surge protector protects the computer from being damaged from high volts every once in a while; spikes or surges.
A Voltage Regulator protects the computer from being damaged by low volts. For example, when the power is lower than usual for a second or two.
A UPS (uninterruptible power supply) protects the computer from power failures. For example, when the power cuts out for a little while. The UPS instantly goes into action and runs the computer for at least five minutes. This gives the user a chance to save all the open work if necessary.
All the aforementioned devices connect between the wall outlet and the power supply.