Power Supplies and System Cooling

1. Which of the following would you use to keep the power supply working properly? (Choose two.)
   1. Surge protector
   2. Extra power supply
   3. UPS units
   4. Multimeter
2. Power supplies are rated using which of the following units?
   1. Amps
   2. Volts
   3. Watts
   4. Output
3. Newer computers’ power supplies typically have which of the following power output ratings?
   1. 300 watts
   2. 400 watts
   3. 250 watts
   4. 500 watts or higher
4. Most power supplies in use today are designed to handle which two voltage ranges? (Choose two.)
   1. 115
   2. 300
   3. 230
   4. 450
5. Which of the following are causes of power supply overheating?
   1. Overloading the power supply
   2. Fan failure
   3. Dirt or dust
   4. All of these options are correct
6. How many pins are used for the main power connection by recent ATX/BTX motherboards with ATX12V 2.2 power supplies?
   1. 24
   2. 48
   3. 32
   4. 16
7. Which of the following steps would you use to remove a power supply?
   1. Shut down the computer. If the power supply has an on-off switch, turn it off as well
   2. Disconnect the AC power cord from the computer
   3. Disconnect power connections from the motherboard, hard drives, and optical drives
   4. All of these options are correct
8. To avoid power supply hazards you must never do which of the following? (Choose two.)
   1. Disassemble the power supply
   2. Put metal tools through the openings
   3. Switch the voltage to 220
   4. Put a smaller power supply in the computer
9. What device provides emergency power to a computer in case of a complete power failure?
   1. UTP
   2. UPS
   3. Power strip
   4. Surge protector
10. What is the minimum time recommendation for a UPS to supply power for an individual workstation?
    1. 30 minutes
    2. 45 minutes
    3. 1 hour
    4. 15 minutes
11. What is the major difference between a UPS and a SPS? (Choose all that apply.)
    1. The battery is only used when the AC power fails
    2. They are on all the time
    3. A momentary gap in power occurs between loss of AC power
    4. They are far less expensive
12. If a system is dead and gives no signs of life when you turn on the computer, which of the following might be the cause? (Choose all that apply.)
    1. Defects in AC power to the system
    2. Power supply failure or misconfiguration
    3. Temporary short circuits in internal or external components
    4. Power button or other component failure
13. All processors require a finned metal device to help with cooling. What is this device called? (Choose two.)
    1. Passive heat sink
    2. Thermal compound
    3. Active heat sink
    4. Chassis heat sink
14. What is the purpose of thermal compound?
    1. Provides the best possible thermal transfer between a component and its heat sink
    2. Provides the best possible thermal transfer between a component’s heat sink and its fan
    3. To negate the effects of thermal contraction and expansion in adapter cards
    4. Provides the best possible thermal transfer between the northbridge and its fan

Answers

1. A, C. To keep your power supply up and running and to help prevent damage from power surges, you should use a surge protector. The UPS will supply power for a short period of time to the computer system in case of total power outage.
2. C. Power supplies are rated in watts, and the more watts a power supply provides, the more devices it can safely power.
3. D. Most newer computers have 500 watt or larger power supplies in them because of the greater number of drives and expansion cards that are available now.
4. A, C. Standard North American power is 115 volts and European power is 230 volts. Some power supplies have a slider on the back to switch between the two voltages.
5. D. All of the listed reasons can cause damage to the power supply as well as overheating your computer.
6. A. Most of the newer power supplies in use today have 24 pins. Older motherboards have a 20-pin connection.
7. D. All of the listed answers are correct. You must disconnect from the wall first, then once inside the computer unhook the connection to the motherboard.
8. A, B. The wire coils inside the power supply retain potentially fatal voltage levels. To prevent shock you should not disassemble them or stick in a metal object such as a screwdriver.
9. B. A UPS (uninterruptible power supply) will keep a standard desktop up and running in case of a complete power outage.
10. D. UPSs are designed to supply power to a computer long enough for you to complete a formal shutdown.
11. A, C, D. When a SPS is used there is a momentary gap, usually about 1ms or less, between when the power goes off and when the SPS starts supplying power. SPSs are also less expensive and are not used at all times.
12. A, B, C, D. When turning on a system that shows no signs of life you must consider all of these as potential problems.
13. A, C. All processors require a heat sink. A heat sink is a finned metal device that radiates heat away from the processor. An active heat sink (a heat sink with a fan) is required for adequate processor cooling on current systems. Some older systems used a specially designed duct to direct airflow over a processor with a passive heat sink (a heat sink without a fan). Most motherboards’ northbridges use passive heat sinks.
14. A. Thermal compound (also known as thermal transfer material, thermal grease, or phase change material) provides for the best possible thermal transfer between a component (for example a CPU) and its heat sink. This prevents CPU damage. The fan and adapter cards should not have thermal compound applied to them. As a side note, most northbridges do not have fans.

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