CompTIA A_ Certification All-In-One Exam Guide, Seventh Edition - Michael Meyers [150]
Figure 10-29 On/off switch for an ATX system
Figure 10-30 Shorting the soft on/off jumpers
Your first task after acquiring a new power supply is simply making sure it works. Insert the motherboard power connectors before starting the system. If you have video cards with power connectors, plug them in too. Other connectors such as hard drives can wait until you have one successful boot—or if you’re cocky, just plug everything in!
Cooling
Heat and computers are not the best of friends. Cooling is therefore a vital consideration when building a computer. Electricity equals heat. Computers, being electrical devices, generate heat as they operate, and too much can seriously damage a computer’s internal components.
The power supply fan provides the basic cooling for the PC (Figure 10-31). It not only cools the voltage regulator circuits within the power supply, but it also provides a constant flow of outside air throughout the interior of the computer case. A dead power supply fan can rapidly cause tremendous problems, even equipment failure. If you ever turn on a computer and it boots just fine but you notice that it seems unusually quiet, check to see if the power supply fan has died. If it has, quickly turn off the PC and replace the power supply.
Figure 10-31 Power supply fan
Some power supplies come with a built-in sensor to help regulate the airflow. If the system gets too hot, the power supply fan spins faster. The 3-pin, 3-wire fan sensor connector plugs into the motherboard directly (Figure 10-32).
Figure 10-32 3-wire fan sensor connector
Case fans are large, square fans that snap into special brackets on the case or screw directly to the case, providing extra cooling for key components (see Figure 10-33). Most cases come with a case fan, and no modern computer should really be without one or two.
Figure 10-33 Case fan
The single biggest issue related to case fans is where to plug them in. Most case fans come with standard Molex connectors, which are easy to plug in, but other case fans come with special three-pronged power connectors that need to connect to the motherboard. You can get adapters to plug three-pronged connectors into Molex connectors or Molex connectors into three-pronged connectors.
Maintaining Airflow
A computer is a closed system, and computer cases help the fans keep things cool: everything is inside a box. Although many tech types like to run their systems with the side panel of the case open for easy access to the components, in the end they are cheating themselves. Why? A closed case enables the fans to create airflow. This airflow substantially cools off interior components. When the side of the case is open, you ruin the airflow of the system, and you lose a lot of cooling efficiency.
An important point to remember when implementing good airflow inside your computer case is that hot air rises. Warm air always rises above cold air, and you can use this principle to your advantage in keeping your computer cool.
In the typical layout of case fans for a computer case, an intake fan is located near the bottom of the front bezel of the case. This fan draws cool air in from outside the case and blows it over the components inside the case. Near the top and rear of the case (usually near the power supply), you’ll usually find an exhaust fan. This fan works the opposite of the intake fan: it takes the warm air from inside the case and sends it to the outside.
Another important part of maintaining proper airflow inside the case is ensuring that slot covers are covering all empty expansion bays (Figure 10-34). To maintain good airflow inside your case, you shouldn’t provide too many opportunities for air to escape. Slot covers not only assist in maintaining a steady airflow; they also help keep dust and smoke out of your case.
Figure 10-34 Slot covers
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