A device providing power to electronic equipment and sometimes designated A, B, or C according to its function of heating vacuum tube cathodes, causing a flow of electron current in plate circuits, or applying a direct voltage in grid circuits.Electrical device that supplies electric power to an electrical load. The primary function of a power supply is to convert electric current from a source to the correct voltage, current, and frequency to power the load. A PSU delivers maximum efficiency with a 40 to 60 percent load. Besides, the performance of a PSU declines with time. So, you better opt for a PSU capable of taking you through your next few upgrades for multiple years. You must buy a PSU that fits inside your PC case. Higher-wattage PSUs tend to be a bit longer to house the additional power components they need. This may create issues with cable routing or even with placing other internal components inside the case. So, it is a must to go for a PSU compatible with your PC case. Different PSUs come with different types of power connectors, including 20/24-pin power, 4-pin ATX12V, 4-pin Molex, floppy, SATA, 6-pin PCI-Express graphics and 8-pin PCI-Express graphics. You must get a power supply with connectors your PC components required