Computers, Laptops & Tablets Accessories & Hardware Supplemental PC Power Supplies You may need an extra power supply for your video card by Mark Kyrnin Writer Mark Kyrnin is a former Lifewire writer and computer networking and internet expert who also specializes in computer hardware. our editorial process LinkedIn Mark Kyrnin Updated on July 06, 2020 Accessories & Hardware The Quick Guide to Webcams Keyboards & Mice Monitors Cards HDD & SSD Printers & Scanners Raspberry Pi Tweet Share Email Gaming PCs that are capable of running several graphics cards often require more wattage than a computer's power supply can handle. A supplemental power supply can give your graphics card the external power it needs to render high-resolution video. Corsair What Is a Supplemental Power Supply? A secondary power supply resides within a desktop computer case, adding additional power capacity to the entire system. These are typically designed to fit into a 5.25-inch drive bay. The incoming power cable is routed through an available card slot on the back of the system. Various component cables run from the supplemental power supply to the internal PC components. Because the most common use for these devices is to power the latest generation of energy-intensive graphics cards, these devices almost always have PCI-Express graphics 6-pin or 8-pin power connectors. Some also feature 4-pin Molex and Serial ATA power connectors for internal drives. Due to the limited size of supplemental power supplies, these tend to be a bit more restricted in the overall maximum power output compared to a standard power supply. Typically, these are rated around 250 watts to 350 watts of output. It's possible to replace an existing power supply in a system with a newer, higher-wattage unit. However, installing a supplemental power supply is generally easier than replacing the primary unit. Why Use a Supplemental Power Supply? In addition to sufficient RAM, you need an adequate power supply for the computer's graphics card to render moving 3D images properly. When a graphics card is installed into a system that either lacks the proper wattage output or lacks the proper power connectors, a secondary power supply is necessary. A supplemental power supply can also be used to provide additional power for internal components, for example, if you're using a large number of hard drives. Some desktop computer systems use proprietary power supply designs, so you can't replace the main power supply. However, you can add a supplemental supply to boost its capacity. Therefore, supplemental power supplies are an excellent choice for expanding the capabilities of a system without completely rebuilding it. Reasons Not to Use a Supplemental Power Supply Power supplies are a major generator of heat within computer systems. The various circuits that convert the wall current down the low-voltage lines inside the system generate heat as a by-product. With a standard power supply, this isn't much of a problem, as it is designed for airflow into and out of the case. Since a supplemental power supply resides inside the case, it creates extra heat. For some systems, this isn't a problem if the system has sufficient cooling to handle the extra heat buildup. Other systems can't cope with this extra heat, which could lead to the system shutting down or potential damage to circuits. Before adding a supplemental power supply, examine your system to see if it can handle the heat burdens it would generate. Avoid installing supplemental power supplies in desktop cases that hide the 5.25-inch drive bays behind a door panel. The door prevents the sufficient flow of air and is more likely to overheat the system.