The most sophisticated cases have frontal USB ports. To use them, you need to connect them to the motherboard of your computer. In this tutorial we will show how this connection must be done.
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Figure 1: Detail of a case with two USB ports on its front (this case has also two jacks from on-board audio).
Nowadays motherboards have four, six or eight USB ports, but normally only two or four of them are directly soldered to the motherboard, at its back. Due to that, we generally two USB ports left in the motherboard. These left ports are usually available in 9- or 10-pin connector, as you can see on Figures 2 and 3. It is in that connector that the USB ports of the front panel of the case should be installed.
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Figure 2: 9-pin USB header on the motherboard where the frontal USB ports should be installed.
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Figure 3: Another example of the 9-pin USB header where the frontal USB ports should be installed. In this case, where we have two connectors available, just one will be used.
The biggest problem is that there is no standardization among the several motherboards manufacturers for the functions of each pin, that is, pin 1 of a motherboard connector may have a different meaning from pin 1 of a motherboard connector from another manufacturer. Because of that, each wire of the USB ports of the front panel of the case use individual connectors. As each USB port uses four wires, your case will have eight wires coming from the front panel, in case your case has two USB ports, which is the most common number.
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Figure 4: Wires from the frontal USB ports of the case.
On each wire connector you can read its meaning, which may be +5V (or VCC or Power), D+, D - and GND. Besides the meaning, in each connector you can read whether the wire belongs to port 1 (or A or X) or to port 2 (or B or Y) of the case. The first step for the installation is to separate the wires according to the port, that is, to separate the wires in two groups: port 1 and port 2.
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Figure 5: Wires from one of the two USB frontal ports of the case.
Next you must install the wires in the motherboard connector. The biggest problem is to know the meaning of each motherboard pin, since this is usually not written on the motherboard. For this task, you will need to check the board manual. There you will find the meaning of each connector pin, as we show on Figure 6. All you have to do is to install each of the wires (+5V, D+, D - and GND) in the correct places as shown in the manual. In the motherboard of our example, the port 1 wires must be connected the following way: +5V to pin 1, D- to pin 3, D+ to pin 5, and GND to pin 7. The port 2 wires must be connected the following way: +5V to pin 2, D- to pin 4, D+ to pin 6, and GND to pin 8. Notice that the meaning of each pin of your motherboard may be different from this example, therefore you will need to check your board manual. Usually the wires of a door will be one side of the connector (odd pins) and the wires of the other port will be on the other side (even pins).
Figure 6: USB header pin-out, from the motherboard manual.
