Motherboard Power Cables
Let's start with the motherboard power cable. It's a very important cable because without it, a system will never boot. Fortunately, it is also fairly easy to identify because it is large and long.
The only identification problem is the difference between a 10-pin and 12-pin motherboard connection. Some motherboards require the former, while others the latter. The reason for the difference is usually power requirements – the 12-pin can provide more juice.
As long as you're using a power supply from a reputable brand built in the last few years, you shouldn't have to worry about compatibility. Modern power supplies use a 10+2 connector. The extra two pins can be removed if not needed.
Besides the 10-pin, you need to hook up the 4-pin cable. The plug for this is usually near the processor socket.
Molex 4-pin and SATA Power Cables
Two other important power connections that are common are Molex and SATA.
Molex 4-pin connectors look like the white power connection displayed above. They are used to connect a number of different components including older hard drives, many optical drives, and cooling systems and fans. Two of these can be used together with an adapter to provide power for a video card that needs a 6-pin PCI Express cable.
On the other side of the image, you can see the black SATA connection. This is mostly used for hard drives and optical drives. It has a characteristic notch on one end, which prevents improper installation.
The image above is an example of an adapter. Normally, these connections come off a power supply individually, or in groups of three similar cables.
PCI Express Power Cables
Although PCI slots provide some power, they don't have the juice to handle most video cards. This is where the PCI Express power cable becomes important.
There are two versions – six-pin and eight-pin. Six-pin is the most common by far, but some larger cards require eight-pin (which can deliver more power) and the fastest cards need either two six-pins or an eight-pin and a six-pin.
Fan 3-pin and 4-pin Power Cables
Tiny in comparison to other cables and connectors, the 3-pin and 4-pin fan connections are used to power system cooling fans. Often they connect to a motherboard directly, but they can also connect to a power supply using a Molex 4-pin adapter.
The difference between the 3-pin and 4-pin is control. With a 4-pin, it's possible to gain fan speed control through BIOS or software if your motherboard supports that feature. With 3-pin that is still possible, but only by varying the voltage to the fan.
SATA is the dominate standard for connecting hard drives to motherboards, and it appears as above. As you can see, it very much looks like the SATA power connection – but it's a little less than half the size. The SATA cable, like the power connection, includes a small notch on one end that prevents improper installation.
These cables also tend to be colored in a solid color, but there's no "code" to them.
The newer SATA 6/Gbps cables are almost identical to the older ones, and use the same connection. However, they are usually labeled and/or have a characteristic "stripe" that is not found elsewhere.
Before SATA, PATA was the dominate method of connecting driver. Although it's no longer very common, it is still found on some motherboards. The CD-burner in my system is connected this way, as I've had it for some time.
These cables are usually among the easiest to find because they are simply massive. They are thin but long and take up a lot of space. Connecting them can be a bit difficult compared to SATA. For more information, read The Differences Between SATA and IDE.
It should be noted, however, that some vendors now sell more slimmed-down variants of IDE cables. Even so, they're still fairly easy to find because the connectors themselves are the largest in any PC besides the 10/12-pin motherboard connection.
Power, Reset and System Light Cables
The power button, reset button, system speaker and hard drive LED on a computer is connected to the motherboard via a series of long, thin cables. These plug in to exposed pins on the motherboard, usually found in the lower right hand corner.
As you can see, these are thin cables, which makes them hard to find. In addition, you have to install them properly. They have a "positive" and "negative" end printed on them, and if installed the wrong way, they won't work.
Motherboards usually label their pins so you know which direction to install the cable, but the type is so small that you may need a magnifying glass to read it.
You might also find a USB labeled cable that looks like this. Typically, it is used to connect front-mounted USB ports, and hooks up to pins in the lower right hand half of the motherboard.
USB is the most common connection used to plug external devices into a computer. It can be found in several places including the back panel of a desktop, the sides of a laptop, the front of a desktop, or even in some cases on a motherboard.
The photo above is an example of a female USB connection. There are several versions of USB from the original 1.0 specification to the current 3.0, which is much faster. However, all versions of USB can talk to each other at a basic level. If you plug a USB 3.0 device into a USB 2.0 port, you'll be limited to USB 2.0 speeds. But the device will still work.
The Digital Visual Interface was introduced in 1999 as a new way to transfer video signals from computers to monitors. It was designed as a replacement for the analog VGA connection, and slowly took over as the new standard.
Today, DVI is being replaced by HDMI, but it's still extremely common. DVI cables are external only, and easy to identify because they are wide and usually have two screw-pins on either side of the connection, which are designed to keep the cable from falling off it is bumped during use.
Although the Ethernet cable looks like a phone cord at first glance, it is much thicker and has a wider connector. This is to accommodate a greater number of internal wires which are used to provide much higher bandwidth.
Wireless is becoming the dominate means of connection today, but Ethernet cords are still important. They provide highly reliable connections that are astoundingly quick. If performance is of concern to you when connecting to the Internet – perhaps you like to play games, for example – Ethernet cables are your best choice.
These are all the common cables in a modern computer. You might have been expecting more, because there are usually numerous cables in a PC – but they're just multiples of the same type. The basics are not that hard to grasp.
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- Build-Your-OwnComputer: Computer Wiring Guide http://www.build-your-own-computer.net/computer-wiring.html