The “brain” of any computer is the central processing unit (CPU). It selects instructions, applies them, executes any required math or logic computations and then stores the results. CPUs use “cores,” each of which is capable of running an independent process. Processors only had single cores until 2005, when the first dual-core processor arrived. This was a game changer for many applications and rapidly led to four, six, eight and even more cores. Today, you can get up to an 18-core CPU, which is overkill for all but the most highly specialized applications.

The two most common CPUs are dual-core and quad-core. While the higher number of cores is appealing, it isn’t always the right choice. Any PC component’s performance will be affected by the surrounding hardware components, the software you’re running and how you use it. Selecting the right CPU starts with understanding how processors and cores work when it comes to the tasks you ask them to perform.

The Basics

Although it’s easy to assume that the more cores a processor has, the faster your computer will be, that isn’t necessarily the case. Each core is capable of handling an independent task, but this only works if the software you’re using is programmed to split tasks between cores. Although many software genres are designed with this in mind (e.g., high-end computer games), a substantial number of programs don’t make this a priority. If your software is only going to run on one or two cores, having four available won’t make a difference.

Another limiting factor on CPUs is that, regardless of whether you have two cores or 18, they all utilize the same RAM and data path to the motherboard. If neither of these is capable of handling the amount of data a CPU can process, you won’t notice a difference in performance. Processors are an important cog in the wheel of your computer’s operating system, but they’re dependent on the other pieces to a more significant degree than almost any other individual component.

One of the crucial aspects of a core is its clock speed, which is essentially how fast that particular core works. If you have a newer dual-core processor with high clock speeds, it will typically outperform an older quad-core with lower clock speeds. Depending on your application, however, you might prioritize more cores (even with slower clock speeds) or fewer, faster cores.

Here are two examples: let’s say you’re using multiple office programs simultaneously: a word processor, an email provider, an accounting package and an inter-office messaging system. None of these require tremendous computing power, but they do comprise multiple disparate requirements. In this case, you’ll notice the best performance out of a quad-core processor, even if it has relatively low clock speeds. On the other hand, if you’re using a dedicated video editing software with high individual requirements, but you typically don’t have any other programs open at the same time, a dual-core processor with high clock speeds will likely provide better results.

Choosing the Right Processor

Let’s bring everything together and simplify what you need to consider when selecting your next CPU.

• Overall computer size. If this is a desktop PC, it doesn’t really matter. However, if you’re working with a laptop, a processor with more cores will generate more heat and suck up more power, which can drive a larger case size and shorter battery life.
• Clock speed. Remember that how many cores you have is only part of the puzzle; how quickly each one works is the other half. If you’re using software that requires a tremendous amount of processing power (think audio and video editing or image design), you’ll need higher clock speeds. Routine office work won’t have this requirement.
• Number of cores. Are you using multiple software applications at once, or do you typically work within a single system? If it’s the latter, is that software designed to split its tasks between several cores simultaneously? The more that your daily work is conducive to being divided among multiple cores, the more appealing a quad-core becomes — even at lower clock speeds.
• The rest of the computer. If you’re emphasizing PC performance, you’ll need to upgrade other components to prevent bottlenecks that will throttle down what your CPU could otherwise deliver. Some of the most critical of these are higher amounts of RAM, a solid-state hard drive and the video card.

Finally, budget is always a consideration. You can spend as much as you want on a processor, but rarely will you have unlimited funds. Carefully considering each of the factors listed above will allow you to choose the right processor for your application without overpaying for performance you don’t need or won’t use.