Overclocking your PC: what it gains and how to do it safely

Overclocking raises the frequencies of the processor, memory or graphics card above the manufacturer's values and usually adds anywhere from a few per cent to the low tens of per cent of performance. The simplest and safest step is to enable the XMP or EXPO memory profile. Manual overclocking of the CPU and graphics card requires suitable components, good cooling and thorough stability testing.

Summary

• Intel processors can only be overclocked in versions with an unlocked multiplier (K suffix) on boards with a Z-series chipset.
• AMD Ryzen processors have an unlocked multiplier, but in practice automatic PBO and Curve Optimizer are used more often.
• You overclock a graphics card with software (e.g. MSI Afterburner), without touching the hardware.
• Verify every overclock with a stress test – an unstable computer is worse than a slower one.

What you can overclock

How much difference simply enabling XMP makes is shown by our measurements in the article RAM system memory.

What you need for overclocking

1. A processor with an unlocked multiplier: on Intel, models with the K (KF) suffix; on AMD, most Ryzens.
2. A suitable motherboard: a Z-series chipset for Intel, a B or X chipset board with good CPU power delivery for AMD.
3. Good cooling: a powerful air cooler or liquid cooling (AIO), and good airflow in the case.
4. A quality power supply with headroom – overclocked components draw more power. We explain how to size a PSU in the article How to choose a PC power supply.

Step-by-step procedure

1. Update the BIOS and note down the default values.
2. Measure performance and temperatures before making changes (e.g. Cinebench, 3DMark).
3. Raise the frequency in small steps, and increase voltage only carefully and within the limits recommended for the processor.
4. Run a stress test after each change and watch the temperatures.
5. If the test fails, go back one step. Leave the final settings running in a stress test for several hours.

When we at PC Praha prepared overclocked gaming builds, we checked stability with a continuous stress test of up to 12 hours. You will find suitable testing tools in the article PC stress test.

Undervolting: the opposite of overclocking, often more worthwhile

Modern processors and graphics cards run close to their limits out of the box. Instead of raising the frequency, it is therefore often more useful to lower the voltage while keeping the same performance. The component then runs cooler, the cooling is quieter and, thanks to the lower temperature, it often sustains higher clocks for longer. On AMD this is done with Curve Optimizer; on graphics cards with the voltage/frequency curve in a tool such as MSI Afterburner.

Risks and warranty

• Manually increasing voltage shortens the chip's lifespan and can damage it.
• Processor manufacturers usually do not cover damage caused by operation outside specification under warranty. Check the terms with the specific manufacturer.
• Unstable overclocking can corrupt data – back up important files before experimenting.

Overclocking ASIC miners has its own rules – we discuss them in the article Does overclocking harm ASICs?

What next

• PC service and upgrades – cleaning, fresh thermal paste and better cooling are the foundation for higher performance.
• Custom PC builds – a build with headroom in both power supply and cooling.