At the heart of every computer is a Central Processing Unit (CPU). It’s the thing that does all of the calculations for a system, whether that means you’re writing a paper for school, sending an email, or online shopping. It’s one of the things that’s most often the focus of PC builders as well, because different CPUs are good for different things. Researchers doing complex linear algebra need different things from their CPUs than gamers do, and gamers need different things than your average home or business user. Here we go through our CPU buying guide for 2021: what to look for in a processor.
Aspects of a CPU
One of the first things you’ll see when looking up a CPU is how many cores it has. This means the number of simultaneous things it can do at once. Each processing core can handle a task – meaning the more cores you have, the more you can do at once. Most CPUs will now have at least four cores, but those are generally only suited to very basic home and office use.
I would recommend somewhere in the neighborhood of six to 12 for gamers, depending on what else you’re doing at the same time, and anywhere from 16 to 64 for workstation users, virtual lab builds, and research, obviously depending on your use case.
The reason I suggest most users not buy 64 core CPUs is because as you add more cores, the cores will move more slowly, and most users will benefit from faster clock speeds to chew through small tasks more quickly. You’ll notice that on AMD’s top-of-the-line Threadripper CPU, the 3990x: clock speeds don’t come anywhere close to the fastest stock clock speed on the market right now, which on paper belongs to the Intel Core i9-10900k, with the 3990x coming in at a base clock of 2.4 GHz and a max boost clock of 4.3 GHz, and the 10900k coming in at 3.7 base and 5.3 boost.
These base and boost clocks refer to multithreaded and lightly threaded workloads, respectively. So the 3990x can push all 64 cores to 2.4 GHz, whereas the 10900k can push all 10 cores to 3.7 GHz.
The Thermal Design Power, or TDP, is the maximum amount of power that a CPU is designed to draw from the computer and the max amount of heat that it will produce. In general, the lower the core count and clock speed, the lower TDP. The higher the core count and clock speed, you’ll generally need more power and produce more heat for a given CPU.
For example, there are low-power laptop chips that have a 15 watt TDP, which is fine because laptops are meant to run on battery power and shouldn’t put out too much heat, but the AMD Threadripper 3990x has a TDP of 280 watts. That doesn’t generally matter, though, as those are put in very large workstations that are capable of dissipating that kind of heat.
There are two primary CPU manufacturers for desktop computers: Intel and AMD. At the moment, there are fewer and fewer use cases where Intel CPUs are better than AMD CPUs due to the engineering going into AMD’s products. The processors are engineered and manufactured with more efficiency built in, and there’s no denying that when the engineering is smarter and the manufacturing is better, that you’ll end up on top. However, there are some situations where you’d want an Intel CPU, and I cover that next.
Overclocking your CPU is something that’s not always recommended, but something you can do. It’s the process of squeaking more power out of your CPU by pushing more electricity into it and asking it for higher clock speeds. Anything in Intel’s lineup with a “k” at the end or in AMD’s lineup with an “x” at the end is overclockable.
Examples of CPUs for Different Use Cases
I’d like to explicitly look at four different use cases and find a CPU for them. This should give you an idea of where you fit into the equation. Please also note that this does not include any Graphics Processing Units, so make sure you check out our Graphics Card Buyer’s Guide for more information on buying a GPU in 2021.
Use Case 1: The Casual User
If you’re a casual user who surfs the Web, works from home, and maybe does a little bit of very light gaming, something like an Intel Core i5-10400 or an AMD Ryzen 5 3600 would do the trick. They’re each 6 cores and have a 65-watt TDP, meaning the included coolers or something relatively small will do the trick. It’s worth noting that the 10400 does have integrated graphics, but the 3600 does not, so you’d have to buy a separate GPU to go along with the 3600. Not a big deal, but just something of note.
Use Case 2: The Gamer
“Gamer” is a pretty nebulous term because you could play anything from Minecraft, which runs on a Raspberry Pi, to Crysis, which doesn’t run well on anything. There are a few ranges here, but an Intel Core i7-10700k or an AMD Ryzen 7 5800x would be a good choice. They’re both eight cores and have great single-thread and multi-thread performance, which is what games are starting to work out.
You could pay more for more performance, especially if you’re planning on working in some light content creation or streaming, but for pure gaming, these are a solid bet. You could spend less on a more powerful 6-core CPU than the previous use case mentions, but a Core i7 or Ryzen 7 is a great option. For the ultimate in gaming performance, the top-of-the-line Intel Core i9-10900k or the Ryzen 9 5900x would be your go-to.
Use Case 3: The Developer or Content Creator
These seem very different, but they’re surprisingly similar: professional, demanding use cases that require some solid “oomph” under the hood. For professional applications, there’s no beating AMD. That’s where they’ve shone past Intel for years, and where they continue to today. A Ryzen 9, either the 5900x or the 5950x, would be an excellent choice. They have 12 and 16 cores respectively, and they deliver excellent single and multithreaded performance. They also operate at a lower TDP than Intel’s most powerful offering, with more real-world performance, more cores, and less heat. Professional applications are a slam dunk for AMD.
Use Case 4: The Engineer or Researcher
The honor here goes to AMD Threadripper. The best of the best chiplets AMD has to offer go into these Threadripper chips, and the core counts vs. the clock speeds are insane. You can get a 32-core processor that absolutely trounces Intel’s eXtreme editions, and that’s to say nothing of the other models in the lineup. If you need high-performance, multicore CPUs for serious work, there’s nothing for it besides Threadripper. When the studio that made Terminator: Dark Fate and the creator of Linux use Threadripper, you know you’re in good company.
I hope you enjoyed our CPU Buyer’s Guide for 2021. If you did, make sure you check out some of our other CPU content, like our comparison of CPU core count vs. clock speed, why CPU clock speeds aren’t increasing, and how to cool down a high CPU temperature.