PC Troubleshooting - Symptoms of a Bad CPU
By Stephen Bucaro
It's very difficult to determine if a failure is caused by the CPU because many other
components can cause the same symptom when they fail.
1. System fails to boot
2. System re-boots intermittently
3. General Protection Fault
4. Illegal Operation
5. Stop Error, or BSoD (Blue Screen OfDeath)
Actually, CPUs rarely fail, and about the only way to determine if the CPU is causing
the failure is to swap it out with a known working CPU of the same type and speed. Since
this is difficult, the best bet is to first rule out every other possibility.
Before suspecting the CPU, rule out all the possibilities listed below.
1. The Operating System
2. A peripheral port device
3. A bad memory module
4. The hard disk drive
5. The power supply
6. The motherboard
If you have ruled out out all the other possibilities, investigate the items listed below.
2. A short circuit
The Primary Killer of CPUs is Heat
Check the items listed below.
1. The CPU fan is operating
2. Case exhaust fans are operating
3. No fan or vent is blocked with dirt
4. CPU fan air flow is not blocked by cables
5. There's sufficient space around case fans and vents for proper air flow
Visually inspect the CPU for mechanical problems. Some of these inspections may require
removal of the CPU fan and CPU.
CPU with Fan
1. The CPU fan is securely fastened to the CPU
2. The thermal compound between the CPU and heat sink appears sufficient
3. Dirt or spilled liquids are not causing a short between pins or traces
4. The pins of the CPU are making positive contact with the circuit board
Note that modern CPUs use ball grid array (BGA) packaging. With BGA packaging, the pins
are replaced by balls of solder stuck to the bottom of the package. The CPU is placed
on a circuit board pads in a pattern that matches the solder balls. The assembly is then
heated causing the solder balls to melt.