Central Processor Unit (CPU) Failures

Plain and simple: If your CPU doesn’t work, neither will your PC. The power supply should engage when the PC is turned on, and the motherboard and other components should roar to life. But if the CPU isn’t available because it has been removed, poorly installed, or has failed, you won’t get farther than the POST process. The CPU isn’t optional equipment; it’s core equipment.

If you try to start your PC one day and receive an error message on the boot screen related to the CPU, you have no choice but to go inside the case. Take these steps:

  1. Turn off the PC and disconnect power.

  2. Remove the PC cover.

  3. Ground yourself using your anti-static wrist strap according to its directions.

  4. Locate your CPU.

  5. Check the CPU’s seating. It doesn’t hurt either to check other aspects of the motherboard and its components to be sure there is no damage or loose boards or connections.

  6. You may want to leave the cover off while you reconnect power, turn the PC on, and try to boot it again.

If the installation is correct and the CPU was working previously without any intervening event that may have damaged it, you may indeed have a dead CPU. You’ll need to get either an exact replacement (meaning the same CPU type, speed, and package type such as a PIII 800 MHz) or another CPU that can fit the range of CPUs supported by your motherboard. Your motherboard or PC manufacturer often provides a list of these on its support web site or by calling their Customer Service representatives.

Checking the CPU Fan

In evaluating a CPU, it’s important to check the status of the CPU’s fan since a malfunctioning or non-operational CPU fan can damage or destroy a CPU because it fails to remove the heated air around the processor. Before this happens, such heat can also shut down your system. Many—but by no means all—motherboards include a thermal sensor feature that automatically shuts down your system when the interior temperature near the sensor reaches a designated peak temperature (which hopefully is below the point at which wires melt and chipsets fail). Thus, if you’ve had unexplained shutdowns or other problems you’ve wondered might be related to overheating, check the CPU fan before you wake up to a dead CPU.

The best way to test a CPU fan—like other fans on your system—is simply to eyeball the fan while it’s in operation. For example, follow the last set of steps for checking your CPU and, after completing step 6 with the cover off, look at the CPU fan (but keep hands and face away) to be sure its small blades are turning.

While the CPU fan is a separate piece of hardware, it is mounted or otherwise attached to the CPU packaging. Because the fan is separate from the CPU, it’s easy to remove the CPU fan for cleaning (compressed air works great), as you can see in Figure 10.2. Built-up dust and debris can slow or stall the fan blades. Just cleaning alone can often turn a malfunctioning fan into a working one. If cleaning doesn’t help, you can usually replace a CPU fan for less than $20, depending on the features of the fan (some get quite elaborate) and the type of CPU packaging involved.

click to expand
Figure 10.2: A Pentium II/III CPU fan removed for cleaning

Photo courtesy of Emily Sherrill Weadock

Tip 

Unless you’re positive the CPU fan works, replace the CPU fan at the time you replace the CPU. It’s always possible that the fan at least contributed to the CPU’s failure, and you don’t want a replacement CPU to fall prey to the same fate. Also, if you change your motherboard and CPU as part of the replacement process, you may need a different CPU fan because of CPU packaging differences between Pentium II/IIIs and Pentium IV systems, AMD Athlon and Duron vs. earlier AMD CPUs, and so on.



PC Disaster and Recovery
PC Disaster and Recovery
ISBN: 078214182X
EAN: 2147483647
Year: 2006
Pages: 140
Authors: Kate J. Chase

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