Computers require two kinds of cable: electrical power cables and data transfer cables. In some cases, data transfer cables handle the electrical power function too, allowing a device to function without a separate electrical connection. If you build a PC from scratch, you should end up with all the cables you need simply by buying the hardware components themselves, which usually come with the necessary cables. For beefy builds you might run out of a certain kind of cable, in which case you’ll need to buy more.
External Electrical Cables
Many external devices, like printers and speakers, require their own electrical power supply. This means they need standard electrical cables that can plug into a surge protector. Your computer’s power supply unit also needs one of these, as will a stand-alone monitor if you have one. If for any reason you need to buy a third-party AC/DC power adapter, make sure you match the adapter’s amperage and voltage specifications to the hardware requirements as exactly as possible.
External Data Cables
Every non-wireless external device needs a data connection to your computer. Many devices use the standardized USB cable format. Make sure any computer you build will have enough USB ports to accommodate these devices. Other devices require different kinds of cables. If you use a wired Internet connection, you probably need an Ethernet cable. Speakers usually require their own kinds of cables, often ending either in a TRS connector or an RCA connector. A monitor requires either a VGA, DVI or HDMI cable. Your printer and scanner, if they don’t use USB, may require a parallel port cable. Your mouse and keyboard, if they don’t use USB, need PS/2 cables. Note that parallel ports and PS/2 ports have become outdated but are still available for sale. Make sure your computer will be able to physically accommodate these kinds of connections if you plan to use them.
Internal Electrical Cables
Every piece of hardware inside your computer needs electrical power, either from the power supply unit or the motherboard directly. Most hardware components that physically plug into the motherboard, like the CPU and RAM, won’t need power cables. A few might, such as the CPU fan, which comes with the necessary cable. Meanwhile, other components such as your video card, hard drive, DVD drive and even the motherboard itself must connect to the power supply unit. The PSU comes with different types of power cables, such as SATA power cables, PCI-express power cables and a special cable for the motherboard. PSUs have a limited number of available power cable connections as well as an overall wattage limit, so make sure you buy a sufficiently robust PSU that will not run out of capacity.
Internal Data Cables
Every piece of hardware inside your computer needs a data connection to the motherboard. External devices plug into the motherboard through a port on the outside of the computer. Inside, you need to use connecting cables. Most internal devices, such as hard drives and DVD drives, use SATA data cables. These cables connect to SATA slots on the motherboard. Devices connecting to the motherboard’s PCI-based slots don’t usually require data cables because design conventions usually call for the devices themselves to plug into the slots on the motherboard, as is the case with modern graphics cards.
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