What is clock in computer architecture

Highlights:

• CPU speed

• Clock speed

• Intel® Turbo Boost Technology

• Why it matters

Clock speed is one of your CPU’s key specifications—but what does it really mean?1

Clock speed is one of your CPU’s key specifications—but what does it really mean?1

The performance of your CPU—the “brain” of your PC—has a major impact on the speed at which programs load and how smoothly they run. However, there are a few different ways to measure processor performance. Clock speed [also “clock rate” or “frequency”] is one of the most significant.

If you’re wondering how to check your clock speed, click the Start menu [or click the Windows* key] and type “System Information.” Your CPU’s model name and clock speed will be listed under “Processor”.

What Is Clock Speed?

In general, a higher clock speed means a faster CPU. However, many other factors come into play.

Your CPU processes many instructions [low-level calculations like arithmetic] from different programs every second. The clock speed measures the number of cycles your CPU executes per second, measured in GHz [gigahertz].

A “cycle” is technically a pulse synchronized by an internal oscillator, but for our purposes, they’re a basic unit that helps understand a CPU’s speed. During each cycle, billions of transistors within the processor open and close.

Frequency is more operations within a given amount of time, as represented above.

A CPU with a clock speed of 3.2 GHz executes 3.2 billion cycles per second. [Older CPUs had speeds measured in megahertz, or millions of cycles per second.]

Sometimes, multiple instructions are completed in a single clock cycle; in other cases, one instruction might be handled over multiple clock cycles. Since different CPU designs handle instructions differently, it’s best to compare clock speeds within the same CPU brand and generation.

For example, a CPU with a higher clock speed from five years ago might be outperformed by a new CPU with a lower clock speed, as the newer architecture deals with instructions more efficiently. An X-series Intel® processor might outperform a K-series processor with a higher clock speed, because it splits tasks between more cores and features a larger CPU cache. But within the same generation of CPUs, a processor with a higher clock speed will generally outperform a processor with a lower clock speed across many applications. This is why it’s important to compare processors from the same brand and generation.

How Does Clock Speed Affect Gaming?

Before the advent of multi-core CPUs, clock speed was viewed as the key spec for comparing single-core processors. Today, it’s taken into consideration alongside number of cores, CPU cache, and power consumption.

The impact of clock speed on an individual game depends on the game’s engine and the tools used to create it. Benchmarking sites like Tom’s Hardware have found that some game engines, like Far Cry: Primal’s Dunia, benefit more from strong single-thread performance than multithreading.2 On the other hand, many newer AAA games, especially in multithreading-friendly engines like Unreal Engine 4, can benefit both from extra cores and increased clock.3

Specific benchmarks are the best way to assess CPU performance in a particular game engine, but clock speed is a good general guide to the relative performance of processors within a product family.

What Does Turbo Frequency Mean?

Intel CPU specifications list both Max Turbo Frequency and Processor Base Frequency. The processor base frequency refers to the CPU’s regular operating point, while the Max Turbo Frequency refers to the maximum speed the processor can achieve using Intel® Turbo Boost Technology.

Intel® Turbo Boost Technology is a tool that enhances clock speed dynamically to deal with heavy workloads. It works without requiring any installation or configuration by the user. The technology judges the amount of thermal headroom the processor has, as well as the number of cores in use, and then boosts clock speed to the maximum safe level. Read more about the technology here.

Which number is more important for gaming? The turbo frequency. Given adequate cooling, this is the speed your CPU will operate at when dealing with heavy workloads [such as traveling through a city, or calculating the AI behavior on an enemy turn in a strategy game] in the most CPU-intensive titles.

How Do You Adjust Your CPU Clock Speed?

The term “overclocking”4 refers to speeding up the CPU clock for more processing power. Intel CPUs with a “K” in the name have an unlocked “multiplier” for easy overclocking when paired with a motherboard chipset that supports overclocking.

Overclocking can yield improved FPS5, even for high-end CPUs like the latest Intel® Core™ i9 processor. Learn more about how to find a stable overclock and get more out of the hardware you already own here.

The CPU multiplier [sometimes called the “CPU ratio”] is multiplied against the CPU Base Clock [or BCLK] to determine the processor’s clock speed. A CPU multiplier of 46 and a base clock of 100 MHz, for example, results in a clock speed of 4.6GHz. [Note that the BCLK in the system’s BIOS settings is not the same as the “Processor Base Frequency” referred to in Intel specs—the latter refers to the overall CPU clock speed when Intel® Turbo Boost Technology isn’t activated.]

The BCLK sets not only the speed of the CPU, but also the speed of memory, PCIe bus, CPU cache, and more. It’s easier for overclockers to simply adjust the CPU multiplier than to change the BCLK, which can cause instability by affecting many components at once.

Why Does Clock Speed Matter?

CPU clock speed is a good indicator of your processor’s performance. Though applications like video editing and streaming are known to rely on multi-core performance, many new video games still benchmark best on CPUs with the highest clock speed.

• What Is Clock Speed?
• How Does It Affect Gaming?
• What Is Turbo Frequency
• Adjust CPU Clock Speed?
• Does It Matter?