CompTIA A_ Certification All-In-One Exam Guide, Seventh Edition - Michael Meyers [153]
Failure to respect the power of electricity will eventually result in the most catastrophic of all situations: a fire. Don’t think it won’t happen to you! Keep a fire extinguisher handy. Every PC workbench needs a fire extinguisher, but make sure you have the right one. The fire prevention industry has divided fire extinguishers into four fire classes:
Class A Ordinary free-burning combustible, such as wood or paper
Class B Flammable liquids, such as gasoline, solvents, or paint
Class C Live electrical equipment
Class D Combustible metals such as titanium or magnesium
As you might expect, you should only use a Class C fire extinguisher on your PC if it should catch fire. All fire extinguishers are required to have their type labeled prominently on them. Many fire extinguishers are multi-class in that they can handle more than one type of fire. The most common fire extinguisher is type ABC—it works on all common types of fires.
Beyond A+
Power supplies provide essential services for the PC, creating DC out of AC and cooling the system, but that utilitarian role does not stop the power supply from being an enthusiast’s plaything. Plus, server and high-end workstations have somewhat different needs than more typical systems, so naturally they need a boost in power. Let’s take a look Beyond A+ at these issues.
It Glows!
The enthusiast community has been modifying, or modding, their PCs for years, cutting holes in the cases, adding fans to make overclocking feasible, and slapping in glowing strips of neon and cold cathode tubes. The power supply escaped the scene for a while, but it’s back. A quick visit to a good computer store off- or online, such as http://directron.com, reveals power supplies that light up, sport a fancy color, or have more fans than some rock stars. Figure 10-40 shows a see-through PSU.
Figure 10-40 See-through power supply that glows blue
On the other hand, you also find super-quiet stealth power supplies, with single or double high-end fans that react to the temperature inside your PC—speeding up when necessary but running slowly and silently when not. One of these would make a perfect power supply for a home entertainment PC because it would provide function without adding excessive decibels of noise.
Modular Power Supplies
It’s getting more and more popular to make PCs look good on both the inside and the outside. Unused power cables dangling around inside PCs creates a not-so-pretty picture. To help stylish people, manufacturers created power supplies with modular cables (Figure 10-41).
Figure 10-41 Modular-cable power supply
Modular cables are pretty cool, because you add only the lines you need for your system. On the other hand, some techs claim that modular cables hurt efficiency because the modular connectors add resistance to the lines. You make the choice; is a slight reduction in efficiency worth a pretty look?
Rail Power
When you start using more powerful CPUs and video cards, you can run into a problem I call “rail power.” Every ATX12V power supply using multiple rails supplies only a certain amount of power, measured in amps (A), on each rail. The problem is with the 12-V rails. The ATX12V standard requires up to 18 A for each 12-V rail—more than enough for the majority of users, but not enough when you’re using a powerful CPU and one or more PCIe video cards. If you have a powerful system, get online and read the detailed specs for your power supply. Figure 10-42 shows sample power supply specs. Many power supply makers do not release detailed specs—avoid them!
Figure 10-42 Sample specs
Look for power supplies that offer about 16 to 18 A per rail. These will be big power supplies—400 W and up. Nothing less will support a big CPU and one or two PCIe video cards.
Watch out for power supplies that list their operating temperature at 25°C—about room temperature. A power supply that provides 500