What Is Overclocking and How Does It Impact Your PC?

Get extra performance from your PC by adjusting some settings

Computer chips have a clock speed, which is the speed at which the chip processes data. Whether it's the memory, CPU, or graphics processor, each has a rated speed. Overclocking is the process by which a chip is run beyond its specifications for added performance. This is possible because manufacturers generally rate a chip below what it can achieve in terms of speed to ensure reliability. Overclocking pulls extra performance out of a chip to get the full potential from a computer.

Why Overclock?

Overclocking boosts the performance of a computer without much extra cost. There are some costs involved in either buying parts that can be overclocked or dealing with the effects of overclocking components. For some users, this means creating a computer system with the highest performance possible because they are pushing the processors, memory, and graphics as far as each can go.

The CPU section in the Processes tab in Task Manager in Windows 10

For other users, it means extending the life of the current computer components without upgrading components. Finally, it is a way to get a high-performance system without spending the money it costs to put together an equivalent level of performance without overclocking. Overclocking a GPU for gaming, for example, increases the performance for a better gaming experience.

How Hard Is It to Overclock?

Overclocking a system depends on what components are on the PC. For instance, many CPUs are clock locked. This means the CPU can't be overclocked or can be overclocked at limited levels. Graphics cards, on the other hand, are fairly open, and most can be overclocked. Similarly, memory can be adjusted like graphics. Still, the benefits of memory overclocking are limited compared to CPU or graphics adjustments.

An example of the BIOS Setup Utility Main Menu

Overclocking any component is generally a game of chance, depending on the quality of the components. Two processors with the same model number can have different overclocking performance. One may get a boost of 10 percent and still be reliable, while another could reach 25 percent or more. You won't know how well it will overclock until you try. It takes patience to slowly adjust speeds upwards and test for reliability until you find the highest level of overclocking.


Often when dealing with overclocking, voltages are mentioned. This is because the quality of the electrical signal through a circuit can be impacted by the voltages supplied to each. Each chip is designed to run at a specific voltage level. If the speeds of the signal through the chips are increased, the chip's ability to read that signal can be degraded. To compensate for this, the voltage is increased, which increases the strength of the signal.

While upping the voltage on a part may increase its ability to read the signal, there are some serious side effects.

  • Most parts are rated to run at a specific voltage level. If the voltage level is too high, you can burn out the chip, effectively destroying it. This is why voltage adjustments are generally not something you should touch when you first start overclocking.
  • Another effect of increasing voltage is higher power consumption in terms of wattage. This could be a problem if the computer doesn't have sufficient wattage in the power supply to handle the extra load from overclocking.

Most parts can be overclocked to some extent without the need to increase the voltages. As you get more knowledgeable, you can experiment with slight voltage increases to boost it. Still, there is always a risk when adjusting these values when overclocking.


One of the byproducts of all overclocking is heat. All processors produce a fair amount of heat and require some form of cooling to function. Generally, this involves heatsinks and fans to move air over the processor. With overclocking, more strain is put on those circuits, which, in turn, generates more heat.

Heat negatively impacts electrical circuits. If circuits get too hot, signals are interrupted, which leads to instability and crashes. Plus, too much heat can lead to the part burning itself out, similar to having too much voltage. Many processors have thermal shutdown circuits to prevent overheating to the point of failing. The downside is that you end up with something that isn't stable and constantly shuts down.

Swiftech H140-X CPU Liquid Cooling System

Why is this important? There must be sufficient cooling to overclock a system properly, or else there's instability due to the increased heat. As a result, computers generally need better cooling in the form of larger heatsinks, more fans, or faster-spinning fans. For extreme overclocking levels, liquid cooling systems may have to be implemented to deal with the heat properly.

CPUs generally require after-market cooling solutions to deal with overclocking. These solutions are readily available and vary in price depending on the materials, size, and quality of the solution.

Graphics cards are more complicated. Replacing the cooling system requires more disassembly and a new cooler to match the exact variant of the card. As a result, the simplest solution for graphics cards is to increase the speeds of the fans, which increases the noise. The alternative is to purchase a graphics card that is overclocked and comes with an improved cooling solution.


In general, overclocking computer components voids any warranties provided by the vendor or manufacturer. This isn't a concern if your computer is older and past any warranties. However, if you attempt to overclock a new PC, voiding that warranty can mean a loss if something goes wrong and there's a failure.

Some vendors offer warranties that protect you in the event of overclocking failure. For instance, Intel's Performance Tuning Protection Plan provides warranty coverage for overclocking eligible parts. These are probably smart things to look into if you are overclocking for the first time.

Graphics Overclocking

The easiest component to overclock in a computer system is the graphics card. This is because both AMD and NVIDIA have overclocking tools built into their driver suites that work with most of their graphics processors.

Generally, all that is needed to overclock a processor is to enable the adjustments of the clock speed and then move a slider to adjust the clock speeds of either the graphics core or video memory. Some adjustments allow for the fan speeds to be increased and, possibly, change the voltage levels.

Gigabyte Radeon R7 360 2GB Overclocked Graphics Card

The other reason that overclocking a graphics card is fairly easy is that instability in a graphics card generally doesn't impact the rest of a computer system. A video card crash generally requires rebooting the computer and returning the speed settings to a lower level. This makes adjusting and testing the overclock a fairly simple process.

Adjust the slider up to a slightly faster speed and then run a game or graphics benchmark for an extended period of time. If it doesn't crash, you are generally safe and can move the slider up or keep it in the existing position. If crashes, you can either back down to a slightly slower speed or increase the fan speed to improve the cooling to compensate for the additional heat.

CPU Overclocking

Overclocking the CPU in a computer is more complicated than the graphics card. The CPU has to interact with the other components in the system. Simple changes to the CPU can cause instability in other aspects of the computer. It's the main reason why CPU manufacturers put in restrictions that prevented overclocking on any CPU. This was referred to as clock locked. Essentially, the processors are restricted to a set speed and can't be adjusted outside of it.

To overclock a processor these days, you must purchase a computer with features to clock an unlocked model. Both Intel and AMD give designations for these processors by appending a K to the end of the processor model number. Even with a properly unlocked processor, you need a motherboard with a chipset and BIOS that allows for adjustments for overclocking.

So what is involved in overclocking once you have the proper CPU and motherboard? Unlike graphics cards, which generally involve a simple slider to adjust the clock speeds of the graphics core and memory, processors are more difficult. This is primarily because the CPU communicates with all the peripherals in the system.

To do this, it needs a bus clock speed to regulate this communication with all the components. If that bus speed is adjusted, the system would likely become unstable as one or more of the components it talks with wouldn't keep up. Instead, overclocking a processor is done by adjusting the multipliers. Adjusting these settings was typically done in the BIOS. Now, more motherboards come with software that adjusts the settings outside of the BIOS menus.

ASRock Extreme Tuning Utility for Overclocking

The overall clock speed of a CPU is the base bus speed multiplied by the multiplier of the processor. For instance, a 3.5 GHz CPU likely has a bus speed of 100 MHz and a multiplier of 35. If that processor is unlocked, it's possible to set the maximum multiplier to a higher level, for example, 40. By adjusting it upwards, the CPU could potentially run upwards of 4.0 GHz or a 15 percent boost over the base speed. Typically, multipliers can be adjusted by full increments, which means a CPU doesn't have the fine level of control that a graphics card has.

This may seem simple, but the problem with CPU overclocking is that power is heavily regulated to the processor. This includes the voltages to different aspects of the processor and the amount of power supplied to the processor. If one of these doesn't supply enough current, the chip becomes unstable in overclocking.

In addition, a bad overclock of the CPU impacts the other devices it communicates with. This could mean that it doesn't properly write data to a hard drive. Additionally, a bad setting can make the system not boot until the BIOS CMOS is reset by a jumper or switch on the motherboard, meaning that you have to start over from scratch with the settings.

Similar to GPU overclocking, it is best to do the overclocking in small steps. This means adjusting the multiplier up a few and running the system through a set of benchmarks to stress the processor. If it can handle the load, adjust the values again until you reach a point where it becomes slightly unstable. At that point, back off until it is completely stable. Regardless, make sure to note the values as you test in case you have to reset the CMOS.

Was this page helpful?