Processor Speed - Cores, Threads, and Clock Speed

Posted by Josh Fewell on Oct 5th 2020

The computing world is full of ways to gauge processor speed, and we have plenty of factors available. This blog post will cover 3 main topics of CPU performance, which are cores, threads, and clock speed. We will look to answer any questions you may have about which factor is most important when buying a CPU. Let’s dive into some of the functions of these parts to gain a better understanding of the role they play

I’ve already done a breakdown of low-level processor function before (https://centralvalleycomputerparts.com/articles/cpus-explained/), So for this article we are just going to focus on the specific areas of the CPU and how they function together. First, we have cores.

Cores

A CPU core is essentially a functioning processor of its own. Each core in a CPU is capable of fetching, decoding, and executing its own instructions. The more cores your CPU has, the more instructions it can execute simultaneously. This can tremendously increase the performance of your computer because you don't have to wait for tasks to be completed before your CPU can start the next one. However, the performance of a multi-core processor depends heavily on the software utilization in the programs you are using. You can think of a CPU as an office and each core is like a cubicle with a worker in it. They are each capable of working on different tasks, but all serve the same ultimate goal.

Threads

You’ve probably seen a second number referring to the amount of cores a processor has. Sometimes shown like this:

The threads in a processor, are the channels that send information to the cores. Until multithreading became popular, processor cores would have one stream of instructions executed at a time, and when they were finished with that task they would wait for the next instruction line.

Back to our analogy with the workers, a thread is equivalent to how many tasks you let each worker have on their plate at once. While each worker can only do one task at a time, when you can divy 2 tasks to each worker, instead of only being able to have 4 tasks on your processor’s plate, now you can have 8.

The graphics below show an example of a 4-core, 4-thread processor, and a 4-core, 8-thread processor.

While processor cores can still only handle one instruction at a time, with multiple threads, a core can always have a constant stream of 8 instructions so it never has to wait for information.

Clock Speed

Enough talk about cores and threads, It’s time to address your CPU’s clock speed. There are two terms to look out for, Let’s take a look at this image again from before:

As you’ll notice, your CPU’s frequency (speed) is measured in hertz. More specifically, in this case, Gigahertz. 1 hertz is how long it takes for your CPU to complete one clock cycle.

1 hertz = 1 cycle per second

1 megahertz = 1 million cycles per second

1 gigahertz = 1 billion cycles per second

Pretty fast, right? Well, to really understand how fast that is, we need to understand what happens in a clock cycle. A clock cycle is the amount of time between two pulses from an oscillator (a device for generating repetitive electric pulses). Clock speed is the amount of pulses from the oscillator that are completed per second. So, a processor with a 3.5GHz clock frequency, completes 3.5 billion clock cycles per second.

Most modern CPUs can complete one instruction or more during a clock cycle, but there are many different processor architectures and designs. So, you can never assume that 2 identical clock speeds are going to produce the same results unless they are the same brand and model.

So what stats should I focus on when buying a CPU?

I usually like to break systems down into 4 categories to decide what hardware is best for my task: Home Computer, Professional Workstation, Gaming System, and Media Workstation. Intel and AMD both follow the, basic, good, better, best pricing/performance model with their CPUs.

Home Computer:

In a home computer, I’m referring to the computer for the house that is used to check emails, play music, or browse the web. In a system like this, heavy workloads aren’t common and you won’t need many processor cores. For your home computer, I would recommend the most basic pricing option with an Intel Core-i3 or an AMD Ryzen 3 (there are even more basic options like the Intel Pentium or Celeron CPUs if you are operating from a very small budget). Here are a couple options from the most recent generation:

Professional Workstation:

In a professional workstation, you’ll be doing tasks like; running multiple spreadsheets, browsing the web, and performing medium duty tasks. The more tasks you need to balance, the more cores and threads you will prefer to have in your system. I recommend the median processor from each manufacturer, like the Intel Core-i5 or AMD Ryzen 5. Here are a few options:

Gaming System:

This is where you start to get some freedom, depending on what games you like to play. Clock speed begins to be a factor in your selection. Before building a system, I would recommend looking at the game websites where they have recommended PC stats for their games. If you’re looking to pretty much run any modern game smoothly, I would continue following the pricing model from Intel and AMD with some options like these:

Media Workstation:

Any profession that involves editing large files, like high resolution video, photoshop files, and other large projects, will require the best hardware you can get your hands on. The sky is the limit in this category (more realistically, your budget is the limit). Whatever you can afford is going to be your best bet. High clock speeds and massive amounts of threads will be helpful. You’re going to want to maximize performance in this line of work. Time is money and you’ll be saving a lot of it by rendering projects more quickly. Here’s a few options:

The bottom line is, there is no single specification that makes a processor faster than others. Processors are designed with specific workloads in mind. Examine what workload you have at hand to determine what specifications will fit your needs.

References:

https://en.wikipedia.org/wiki/List_of_Intel_Core_i9_microprocessors

https://en.wikipedia.org/wiki/Ryzen

https://en.wikipedia.org/wiki/Coffee_Lake

https://www.howtogeek.com/194756/cpu-basics-multiple-cpus-cores-and-hyper-threading-explained/

https://www.tomshardware.com/reviews/cpu-buying-guide,5643.html

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