Why does one CPU core work harder than others?

Modern CPUs are now capable of featuring a remarkable number of cores, pushing up the performance ceiling to all-new heights.

For example, the Intel Core i9-14900K desktop processor is packed with 24 cores, making it far more powerful than the more basic dual-core quad-core chips.

However, anyone with a PC may have noticed that most computer-based workloads will only utilise a single core. That may prove frustrating for those who have invested so much money into a processor with so many cores, so why does this happen? 

We’ve created this guide to explain why one CPU core will generally work harder than the test, and why this shouldn’t be cause for concern for your PC. 

One core to rule them all

If you check your CPU performance via Windows task manager, you’ll likely see that the vast majority of your processor’s workload has been given to Core 0, rather than splitting them evenly across all of the available cores. 

This is because most workloads don’t require the use of multiple cores. Basic tasks such as browsing the web or using a single application are not very intensive on the processor, and so will usually only require the performance of a single core. 

It would be entirely possible for the likes of Windows to distribute the performance more evenly, but upping the frequency of multiple cores will cause the chip to consume more power, which is wasteful if a single core could comfortably cope with the same workload.

It’s actually fairly rare for an application to make use of all of your cores, especially if you have a 24-core desktop chip. Even intensive workloads such as gaming probably won’t make full use of all of your cores. 

Wasted potential

The vast majority of games only require a small number of CPU cores in order to run on your PC. 

For example, Cyberpunk 2077 is one of the most technically intensive games available, and yet recommends a quad-core Intel chip for the minimum requirements. The recommended specs list a more powerful 12-core processor instead, but it’s still a far cry from the 24-core chips that are now available. 

Cranking up the CPU count is unlikely to cause a significant performance boost either. Sticking with Cyberpunk 2077 at a 1080p resolution, we recorded a 224fps average performance with the 14-core Intel Core i5-14600K chip, while upgrading to the 24-core Intel Core i9-14900K saw an average performance of 221fps. While this looks like a drop in performance, this is likely just a minor fluctuation, instead indicating that the two chips are capable of an almost identical performance for this specific game. 

Cyberpunk 2077 isn’t designed to make use of more than eight cores at a time, so additional cores are effectively wasted here. This means that, as long as you have at least eight cores, the single-core performance will generally be the biggest determining factor to determine how influential a CPU will be on your PC’s gaming performance. 

Like with most games, Cyberpunk is more reliant on the GPU when it comes to performance. Upgrading your GPU will likely have a far bigger effect on performance than upgrading to a processor with more cores. There are certain games that are more CPU intensive than usual, such as the Total War and Civilization series, but GPU performance remains the most important factor. 

Multi-core fun

After establishing that most computer workloads don’t actually require a large number of cores, you may be wondering what the point is in investing in a 24-core desktop chip. Well, there are specific workloads that do make use of such processing power. 

Multiple cores are more useful for applications that are likely to run multiple complex processes simultaneously. This includes workloads such as video editing, 3D animation and batch processing. 

Adobe claims that Premiere Pro runs at 93-98% efficiency with eight cores, while a whopping 32-core setup is suggested for demanding workloads in After Effects when taking full advantage of Multi-Frame Rendering.

If you find yourself running these sorts of applications, you’ll likely find your CPU utilising more cores than usual in order to deliver the required performance. Performance is likely to scale up when using more cores with such apps, whereas that isn’t the case with more simple processes.

And while we’ve established that video games don’t necessarily require a lot of cores, it’s a different story if you want to record footage or broadcast live gameplay, as more cores are required to perform all of these different tasks simultaneously.

With all of this in mind, you should really consider how many cores you’ll likely need from a CPU before buying one. If you’re going to be sticking to basic tasks, then it’s likely you’ll be wasting the potential of the majority of cores in a high-end processor. But the extra cores may well come in handy when dealing with more complex workloads or running multiple processes at one time.