Overclocking is a Bad Idea

I see a lot of forums issues related to problems that are ultimately traced back to overclocking on systems. Overclocking is probably the single worst thing you can do for the lifespan of your PC and the instability caused by overclocking far outweighs any possible performance gains. Professional systems engineers don't overclock systems, and home users shouldn't either for a vast number of reasons. I'll go through a few of them in this post.

What is overclocking?

Overclocking refers to modifying a computer system component in a way that it is operating at a higher frequency/clock rate, voltage, or other measure of performance. Most overclocking is done by people who are conducting experiments with hardware to determine the maximum stress point that a motherboard, processor (CPU), system bus, graphics processing unit (GPU), system memory (RAM), or hard drive can handle before reaching a failure point.

Some misguided individuals overclock their systems and use the overclocked state for their standard configuration. These individuals typically feel the pain shortly after overclocking and they tend to go running to the various hardware forums on the Internet to say that their system is acting up.

Why is overclocking good?

To show the other side of the story, overclocked systems typically have a higher level of performance than their non-overclocked counterparts. These systems typically process numeric calculations, graphics operations, and other system functions at higher rates and appear more responsive to the end user. This comes at a major cost to the system's stability and

Why is overclocking bad?

It immediately voids your warranty for most components. Hardware vendors don't support running system components above their default thresholds. They set these limits after doing numerous tests to determine the right mix between component longevity, performance, and failure rate. Most vendors can detect if a component was overclocked when it failed, and if it happens, it typically voids an RMA request or a warranty repair and the component has to be repurchased by the end user. 

Think about it in the context of how a car operates. Overclocking runs a component at or above the "redline" RPM level for an extended period of time. Even with appropriate cooling, this substantially increases component wear and exponentially increases the probability of component failure. For a car running above the "redline" level, the engine will seize after a short  period of time, even with appropriate cooling and lubrication.

Overclocking throws off the system timing, increasing the probability of memory, hard drive, and processor cache/instruction corruption. The system is designed to have the processor and bus communicate with the other components at a specified rate, increasing the rate of operation can potentially overrun other system components and cause corruptions in calculations performed by the system and sent to/from other components.

Some components cannot be overclocked effectively. An example is a graphics processing unit. Although AMD (ATI) and Nvidia have developed experimental applications for overclocking a GPU, this causes increased stress on a system that does not have adequate dedicated cooling to begin with. Additionally, GPUs have a poor track record of enhancing system stability and adding nonstandard timings/voltage creates another variable that can contribute to increased timeout detection and recovery (TDR) activity/failures in Windows and general GPU related hangs and system failures in Linux/UNIX.

The bottom line is simple... don't overclock your system. The risks outweigh the benefits and overclocking often creates more problems than it solves. If you do overclock and break something, then don't go crying to anyone else because you ultimately did something stupid and received a fair reward. Don't ask the manufacturer for help, because they will find out that you overclocked and that your warranty/support agreement is void.

For end users... don't buy an overclocked system. This is a dangerous scenario if you are storing important documents and potentially irreplaceable data like family pictures on the system. Some unscrupulous computer people will sell these "gaming" systems to you, but if you want faster hardware, then buy faster hardware instead of overclocking cheaper and error-prone hardware. The cost difference typically pays itself back when it is compared to the downtime that overclocking typically causes.

Real computing professionals don't overclock systems. They know the risks and know that the risks outweigh the rewards. Those who do overclock typically have a spare system that they use for experiments, but don't store any real data on because of the increased risk of failure. Overclocked systems are mainly used to answer "what if" type questions and if you really need to have an extra system and willingness to lose this system (or parts of it) to answer these questions.

See Also,
How to Rescue Files From a Damaged Account

Windows Crash Dump Analysis
0x124 WHEA_UNCORRECTABLE_ERROR
0x9C MACHINE_CHECK_EXCEPTION.
Troubleshooting Memory Errors
How to Detect a Failing Hard Drive
Stress Testing a CPU to Detect Hardware Failure
Stress Testing a Video Card