A computer case has buttons to control the power to the motherboard and lights to indicate motherboard activities. You must connect these buttons and lights to the motherboard with the cables from the front of the case. Figure 1 shows some of the front panel cables commonly found in a computer case. Figure 2 shows a common system panel connector on a motherboard where the cables are connected. Writing on the motherboard near the system panel connector shows where each cable is connected.
System panel connectors are not keyed. The following guidelines for connecting cables to the system panel connectors are generic, because no standards for labeling the case cables or the system panel connectors are defined. The markings on your front panel cables and system panel connectors may be different from what is shown. Always consult the manual of your motherboard for diagrams and additional information about connecting front panel cables.
Power and Reset Buttons
The power button turns the computer on or off. If the power button fails to turn off the computer, hold down the power button for 5 seconds. The reset button restarts the computer without turning it off. Some motherboards do not support a reset button. In this case, you might need to depress the power button for a short time to reboot the computer.
Each front panel cable has a small arrow indicating pin 1, as shown in Figure 3. To connect the power button, align pin 1 of the front panel power button cable with the pin marked PWR. To connect the reset button, align pin 1 of the front panel reset button cable with the pin marked RESET.
Power and Drive Activity LEDs
The power LED remains lit when the computer is on and blinks when the computer is in sleep mode. The drive activity LED remains lit or blinks when the computer is reading or writing from the hard drive. Each pair of LED pins on the system panel connector has pin 1 marked with a plus sign (+), as shown in Figure 4. To connect the power LED, align pin 1 of the front panel power LED cable with the pin marked PLED+. To connect the IDE LED, align pin 1 of the front panel drive activity LED cable with the pin marked IDE_LED+.
The motherboard uses the system speaker to indicate the computer’s status. (The system speaker is not the same as the speakers that a computer uses to play music and other entertainment audio.) One beep indicates that the computer started without problems. If there is a hardware problem, a series of beeps is issued to indicate the type of problem. Diagnostic beeps are discussed later in this chapter.
The system speaker cable typically uses four pins on the system panel connector. To connect the speaker, align pin 1 of the front panel system speaker cable with the pin marked + or +5V.
USB ports are located on the outside of many computer cases. USB motherboard connectors often consist of 9 or 10 pins arranged in two rows, as shown in Figure 5. This arrangement allows for two USB connections, so USB connectors are often in pairs. Sometimes the two connectors are together in one piece, as shown in Figure 6, and can be connected to the entire USB motherboard connector. USB connectors can also have four or five pins or individual groups of four or five pins.
Most USB devices only require the connection of four pins. The fifth pin is used to ground the shielding of some USB cables. To connect the USB port, align pin 1 of the USB cable with the pin marked USB +5V or +5V.
CAUTION: Make sure that the motherboard connector is marked USB. FireWire connectors are very similar. Connecting USB cables to FireWire connectors causes damage.
New cases and motherboards may have USB 3.0 capabilities. The USB 3.0 motherboard connector is similar in design to a USB connector, but has additional pins.
Some cases have audio ports and jacks on the outside to connect microphones, external audio equipment such as signal processors, mixing boards, and instruments. Special audio panels can also be purchased and connected directly to the motherboard. These panels can either install into one or more external drive bays or be standalone. Due to the specialized function and variety of the hardware, consult the documentation of the motherboard, case, and audio panel for specific instructions for connecting the cables to the motherboard connectors.
To install front panel cables, follow these steps:
Step 1. Plug the power cable into the system panel connector in the location marked POWER.
Step 2. Plug the reset cable into the system panel connector in the location marked RESET.
Step 3. Plug the power LED cable into the system panel connector in the location marked power LED.
Step 4. Plug the drive activity LED cable into the system panel connector in the location marked IDE LED.
Step 5. Plug the speaker cable into the system panel connector in the location marked SPEAKER.
Step 6. Plug the USB cable into the USB connector.
Step 7. Plug the audio cable into the audio connector.
Generally, if a button or LED does not function, the connector might be improperly oriented. To correct this, shut down the computer and unplug it, open the case, and turn the connector around for the button or LED that does not function.