How to choose a CPU

The central processor, or CPU, is the heart of any PC or laptop, whether it’s a blazing-fast gaming machine or a more demure system for work or school. Depending on what you want to do with your system, buying the one with the right CPU can be the difference between smooth and comfortable performance and a sluggish experience that leaves you tearing your hair out.

Buying the right CPU can be confusing. Cores, threads, clocks, and cache are all numbers that we have ready access to, but making sense of them needs a little know-how. By the end of this CPU buying guide, you’ll know how to choose a CPU, what to look for, and, just as crucially, why.

Feel ready to buy your new CPU already? Here are the best processors from AMD and Intel, and the best all round CPUs for gaming.

AMD vs. Intel

Stock photo of Intel 9th gen core processor
Intel Newsroom/Intel Corporation

There are two main CPU manufacturers when it comes to desktop PCs and laptops: AMD and Intel. Until 2017, unless you were going ultra-budget, Intel was the only real choice. Today, our CPU buying guide can be quite different. Whether you opt for an AMD or an Intel CPU, as long as you buy the right one for what you want to do with your new system, you’ll have a fantastic experience.

That’s not to say that there aren’t instances where we’d likely recommend one company’s products over the other, but the difference isn’t as important as it once was, and there are other factors that may be more important for you.

One important note, however, is that if you are planning to build a computer (here are some helpful tips on how), you must buy compatible components. An Intel motherboard will not work with an AMD CPU, and vice versa.

You can use an Intel SSD in an AMD motherboard or an AMD graphics card in an Intel PC, but when it comes to CPUs and motherboards, stick to just one company.

CPU labels and generations

CPU generations are usually a good way to gauge performance, with newer, higher-number generations typically offering greater performance, improved efficiency, and better features than their predecessors. That is still the case with AMD’s Ryzen processors, with second-generation Ryzen 2000 chips being faster than their first-generation counterparts, and third-generation Ryzen 3000 CPUs offering much-improved performance over their second-generation equivalents.

It’s not quite so clear-cut in laptops, where Ryzen mobile CPUs are based on previous-generation technology. For equivalent Ryzen 3000 desktop performance on a laptop, you need Ryzen 4000 CPUs. For Ryzen 2000-like performance on a laptop, you need Ryzen 3000. Even so, the later generations are better and offer the best performance available for AMD CPUs.

Similarly, Ryzen 9 CPUs, like the 3950X, are faster than Ryzen 7s like the 3700X. Ryzen 7s are faster than Ryzen 5s, and Ryzens 5s are faster than Ryzen 3s, assuming they’re of the same generation.

Intel’s lineup of CPUs is a little more confusing. It has eighth-, ninth-, and two tenth-generation CPU ranges all available as of Spring 2020. Its ninth generation is slightly faster than its eighth on both laptops and desktops, but the ninth lacks hyperthreading (more on that later) on mid-range CPUs, so multithreaded performance in those chips isn’t always as strong as their eighth-generation counterparts.

Tenth-generation Comet Lake CPUs, like the 10980HK and 10400H, offer the highest processor performance of Intel’s mobile CPUs, but comparably poor graphics to the other tenth-generation CPUs based on Ice Lake technology. Typically, you want to look at Ice Lake for general compute performance and Comet Lake laptops with dedicated graphics cards for gaming.

Cores and threads

AMD Ryzen 9 3900x
Dan Baker/Digital Trends

If you want to know how to choose a CPU, you need to consider cores and threads. Cores are like individual processors of their own, all packed together on the same chip. Traditionally, they can perform one task each at a time, meaning that more cores make a processor better at multitasking. Modern software is far better at taking advantage of more cores at once to do the same job, so more cores can make some software work faster, too.

Threads are the number of tasks that a CPU can conduct at any one time. Many modern processors feature simultaneous multithreading (called hyperthreading on Intel CPUs), which lets each core perform two tasks at once. That’s why you’ll often see a CPU listed with four cores and eight threads or six cores and 12 threads. These additional threads aren’t as fast as the cores themselves — as they are effectively leveraging parts of the CPU that are underused — but they do typically improve performance by a noticeable margin.

Some software can leverage more cores and threads than others, making the number of cores and threads that your CPU has a big indicator of potential performance. Having more cores than you need doesn’t speed things up beyond the limits of what the software can handle, and it can lead to your individual cores not being as fast as those in chips with smaller numbers.

If you just want to answer emails, browse the internet, and watch Netflix, a dual-core will suffice, though you’ll find your experience quicker with four cores, especially if you like to multitask on your system. Budget six-core CPUs are worth considering, too — especially if they have simultaneous multithreading, like AMD’s low-end hexacore designs.

If you’re a gamer, you want at least a quad-core CPU and preferably one with support for eight threads. There are benefits to going with a six-core CPU, and some games can be made moderately faster by going for eight cores. Beyond that, you’ll see very diminishing returns — there’s a reason the fastest gaming processor in the world is the eight-core Intel 9900K.

If you’re a video or audio editor, transcode video, or work with large databases, then the sky is almost the limit with how many cores you can leverage — though as you move beyond eight cores, you won’t see such great leaps in performance. Still, AMD’s 12- and 16-core Ryzen 3900X and 3950X CPUs are two of the best multithreaded CPUs in the world, showing that cores can really help if you’re looking to do a lot of work.

There are even CPUs with as many as 64 cores out there, but they are inordinately expensive and only worth considering for professionals.

Clocks and IPC

AMD CEO Dr Lisa Su details the Ryzen 3700X performance.

Another major consideration with CPUs is clock speed. This is the megahertz (MHz) and gigahertz (GHz) rating and represents how many collections of tasks a processor can perform each second. It’s a fair representation of the speed of individual cores. Though it doesn’t tell the whole story, if two processors from the same generation have the same number of cores but one has a higher clock speed, it will perform faster.

Since higher clock speeds mean individual cores run faster, that can make chips with higher clock speeds but fewer cores perform better in certain applications that can’t make use of higher core and thread counts. That’s why Intel’s 9900K is the fastest gaming CPU, because even though it has fewer cores than a chip like the AMD Ryzen 3900X (eight versus 12), it runs at a higher clock speed — up to 5.0GHz on a single-core versus up to 4.6GHz.

That’s not the whole story, though. CPUs also have different instructions per clock (IPC) ratings. That’s the number of tasks it can perform in each clock cycle, and it’s dependent on the underlying architecture. AMD’s Ryzen 3000 CPUs use the Zen 2 architecture, which has a higher IPC rating than Intel’s ninth-generation Coffee Lake design. That means that when clock speeds are equal, the AMD processors are faster. This is where newer, more advanced designs can really play a part in making a processor more powerful, even if core counts and clock speeds are similar or lower.

While this might seem a little confusing, it highlights the importance of looking at individual reviews for processors. Head-to-heads, where two CPUs are pitted against each other in comparable tests, are also a great way to see how they perform in the real world.

If you want a good rule of thumb, CPUs with higher clock speeds and newer architectures are faster at just about everything, but if you want pure gaming performance, clock speed is king, for now.

Integrated graphics

CPUs can also include integrated graphics chips on the same die, making them capable of operating independently of dedicated graphics cards. Intel CPUs with the F designation (such as the 9900KF) don’t have onboard graphics, but most others do in some form. They aren’t typically powerful, but an entry-level integrated graphics chip like the UHD 620 can do between 30 and 60 fps in older esports games like CS:GO. You’ll want to keep the settings low to avoid stuttering frame rates during intense action or when heavy smoke is deployed.

Intel’s 11th-generation graphics chips (found in tenth-generation Ice Lake processors only, at this time) come in Iris Plus configurations and do offer reasonable gaming performance. In Anandtech’s testing, a 64 execution unit GPU, onboard the Core i7-1065G7 in a Dell XPS 13, managed over 43 fps in DotA 2 at enthusiast detail settings at 1080p. We found it more than capable of playing Fortnite at 720p and 1080p. This is a big improvement over what we’ve seen with Intel onboard GPUs in recent years.

They’re still not a patch on dedicated graphics cards, but they are more than capable of handling basic esports games at lower detail settings.

AMD’s processors typically don’t include onboard graphics on desktop, though there are some accelerated processing units (APU) that do. They’re more comparable to Intel’s 11th-generation graphics, offering reasonable performance in entry-level and esports gaming settings.

All of AMD’s mobile CPUs include onboard Vega graphics, and in some configurations, they can be decent for gaming. We found the RX Vega 10 on a Ryzen 7 3700U-equipped laptop to be more than capable of comfortable frame rates in Diablo 3 and Half-Life 2. You’ll need to check reviews of individual CPUs to see how capable they are, as there are other factors that can affect gaming performance, but know that a higher number of graphics cores typically leads to greater graphical performance.

Power and thermals

PC build-out guide
A Digital Trends staff member installing an all-in-one CPU watercooler. Bill Roberson/Digital Trends

Performance is the most important factor for most CPU purchases — after all, if you can’t do what you want with your new chip faster than you could before, what’s the point in upgrading? If you’re looking to have a quiet PC, an efficient PC, or one that’s particularly compact, power and thermal demands are an important consideration, too.

Unfortunately, neither AMD or Intel give particularly clear data on the power and thermal demands of their processors, instead resorting to bundling the two together into a rating of Thermal Design Power (TDP). This is expressed in wattage, and it gives you a rough idea of how much power the CPU will require from the power supply and how capable a cooler you’ll need to keep it within safe operating temperatures.

Low-power laptop CPUs operate at between just a few watts and up to 45W in the most powerful of gaming machines, while desktop processors can reach up to 125W in some cases, though they are more typically somewhere between 65W and 95W.

In some circumstances, TDP can also be a loose guide to the quality of a processor’s underlying silicon, where more capable CPUs are placed in the higher TDP categories due to their ability to handle additional power. This is very much on a case-by-case basis, though, and no guarantee of a better quality chip. It’s also only really relevant for overclocking.

You’ll need to look at individual processor reviews to see how much power and cooling they actually require, but if you’re buying higher TDP CPUs that require close to 100W, bigger and more capable coolers would be a good consideration if you want a quiet PC.

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