How to Buy the Right CPU

Whether you’re building or upgrading a new PC, the CPU matters a lot. Increased clock speeds and core counts can make a huge difference in overall performance, providing a more responsive system, smoother game play and faster turnaround on intensive tasks such as video transcoding. Plus, the chip you choose will also dictate your motherboard purchase, as each CPU requires only works with a specific socket and set of chipsets.

If you already know a lot about CPU specs and want recommendations, check out Best CPUs page. But no matter desktop processor you get, here are some things to keep in mind.

TLDR:

  • You can't lose with AMD or Intel: So long as you’re considering current-generation parts (AMD Ryzen 2000 or Intel 8th Generation Core “Coffee Lake”), this debate is basically a wash, with Intel doing a bit better on gaming and browsing and AMD handling tasks like video editing faster.
  • Clock speed is more important than core number: Higher clock speeds translate to snappier performance in simple, common tasks such as gaming, while more cores will help you get through time-consuming workloads faster.
  • Get the latest gen: You won't save much money in the long run by going with an older chip.
  • Budget for a full system: Don't pair a strong CPU with weak storage, RAM and graphics.
  • Overclocking isn’t for everyone: For most people, it makes more sense to spend $20-$60 more and buy a higher-end chip.

AMD or Intel: Which Should You Get?

Up until 2017, AMD was the clear underdog, but with its Ryzen and now Ryzen 2 (2000 series) chips, the company has achieved performance parity with Intel. Some fans will have strong opinions, but if you don't have your heart set on one brand or the other, you should be open to either.

Intel still holds a slight lead in IPC (instructions per cycle, or how many instructions a chip can execute in a given time), which makes its chips better for lightly-threaded tasks (many games, web surfing and some Adobe software). AMD tends to offer more cores and threads, which makes it better for professional-grade video editing and animation.

What do you want to do with your CPU?

While it's tempting to just spend as much as you can afford for a CPU, you might be better off saving some of your cash for other components. Determine your processor type and max budget based on what you need your computer to do.

  • Basic tasks: $50-$100 range. If you’re only after a chip that will let you watch video, browse the Web, and do basic productivity tasks like word processing and light spreadsheet work, then an entry-level chip with two or four cores might be just what you need. But if you often find yourself doing more than one of those basic tasks at once, it would be better to step up a model or two. Consider a Ryzen 3 or Intel Pentium on the high end of this price range and an Intel Celeron or AMD Athlon on the low end.
  • Gaming: $150-$250 range. If you’re primarily interested in gaming perfromance, you need at least a mid-range Intel Core i5 or AMD Ryzen 5 CPU. Considering that the graphics card is more important for gaming than the processor, you can save money by not getting a more powerful Core i7 or Ryzen 7 chip.
  • Creative media work or overclocking: $250 - $350 range. If you want more cores or speed for things like video editing—or you just want a fast, capable system with extra overhead for future computing tasks, splurge on a Core i7, Core i9 or Ryzen chip. These are also the chips you'd consider if you want to overclock, though AMD’s lesser Ryzen chips are overclockable as well.
  • Workstation muscle: $400+. If you often find yourself waiting minutes or hours for your current system to render your 3D animation or 4K video, or you’re dealing with massive databases and complex math, consider an Intel Core X or AMD Threadripper CPU. These beasts offer massive amounts of physical cores (up to 18 as of this writing) for extreme multitasking (ex: gaming at high settings while streaming and editing) or time-consuming compute tasks. Business users can consider an Intel Xeon or AMD EPYC processor, but those aren't consumer friendly.

What generation CPU do you need?

Each year or so, Intel and AMD upgrade their processor lines with a new architecture. The current generation for Intel is the company's "8th Gen Core Series," which is also code-named "Coffee Lake." AMD's latest chips are part of its Ryzen 2000 (aka Ryzen 2) line. When looking at the model number, you can see the generation as the first digit of the four number (ex: the 8 in Core i7-8400 or the 2 in Ryzen 7 2700X).

Note that both companies haven't yet updated their extreme chips to the current generation. So the latest and greatest Intel X series CPUs you can get are still 7th gen and the newest AMD Threadrippers are in the Ryzen gen 1 (1,000 series).

While you can still find older processor generations for sale, we wouldn't recommend choosing one, unless you are sticking with a motherboard that doesn't support the latest chips. You usually don't save a lot of money by going with a last-gen processor, either. For example, at press time, the price difference between an outdated 7th-Gen, Core i5-7400 (7th Gen) and its replacement, the 8th Gen Core i5-8400 was just one dollar.

How do you read the model names and numbers?

The jumble of brands and numbers that make up a CPU product name can be confusing. Intel and AMD both break down most of their chips into three “good, better, best” categories, starting with Core i3/Ryzen 3, stepping up to Core i5/Ryzen 5, and ending (in the mainstream chip space, at least) with Core i7/Ryzen 7. Intel has Core i9 as a new extreme/premium tier (see the Core i9-7980XE, priced at around $2,000). but for the vast majority of users, these chips are unnecessary and well out of most people’s price ranges.

For users on a tight budget, Intel offers its Celeron and Pentium chips (Pentium is slightly faster) while AMD has its Athlon line. On the extreme high-end, you'll find AMD's Threadripper and Intel's Core X series, along with the Core i9 (mentioned above).

Now, what about the model numbers that come after the 3, 5, or 7? The first digit designates the product generation (Intel’s Core i7-8700 is an 8th Generation Core processor, and AMD’s Ryzen 5 2600 is a 2nd Generation Ryzen processor. The rest of the numbers just mark various models in the line, with higher generally being better (with more cores and/or higher clocks), while a “K” at the end of an Intel chip means it’s unlocked for overclocking. Only a handful of mainstream Intel chips are “K” skus, while all of AMD’s Ryzen processors are unlocked for overclocking (no “K” designation required). An X at the end of AMD model numbers means higher clock speeds.

Should you overclock?

Overclocking, the practice of pushing a CPU to its limits by getting it to run at higher-than-specced clock speeds, is an art form that many enthusiasts enjoy practicing. But, if you're not in it for the challenge of seeing just how fast you can get your chip to go without crashing, overclocking isn't worth the money.

In order to make your CPU achieve higher clock speeds than it is rated for out of the box, you'll likely spend extra on an enhanced cooling system and an overclocking-friendly motherboard. While all recent AMD chips are overclockable to some extent, if you want to dial up an Intel chip, you'll have to pay extra for one of its K-series processors. By the time you factor in all these extra costs, you'd be better off budgeting another $50-$100 for a CPU that comes with higher clock speeds out of the box. And remember, even if you do get all the right equipment, you could still damage your CPU by pushing it too hard or end up with less-than-stellar results.

What are the key CPU specs and which should I care about?

If you're looking at a spec sheet for a given CPU, you'll see a lot of numbers. Here's what to look out for.

  • Clock speeds: Measured in gigahertz (GHz), this is the speed at which the chip operates, so higher is faster. Modern CPUs adjust their clock speeds up or down based on the task and their temperature so you'll see a base (minimum) clock speed and a turbo (maximum) speed listed.
  • Cores: These are the processors within the processor. Modern CPUs have between two and 18 cores, with most processors containing four to eight. Each one is capable of handling its own tasks. Unless you're a bargain-hunter, you want at least four cores.
  • Threads: This is the number of independent processes a chip can handle at once, which in theory would be the same as the number cores. However, many processors have multithreading capability, which allows a single core to create two threads. Intel calls this Hyper-Threading and AMD calls it SMT (Simultaneous Multithreading). More threads means better multitasking and enhanced performance on heavily-threaded apps such as video editors and transcoders.
  • TDP: The Thermal Design Profile (TDP) is the maximum amount of heat that a chip generates, as measured in watts. By knowing that--for example--the Intel Core i7-8700K has a TDP of 95 watts, you can make sure you have a CPU cooler that can handle that amount of heat dissipation and also that your PSU can provide enough juice.

    It's good to know what your TDP is so you can get the right cooling and power equipment to support your CPU. Also, a higher TDP usually coincides with faster performance.
  • Cache: A processor's on-board cache is used to speed up access to data and instructions between your CPU and RAM. There are three types of cache: L1 is the fastest, but cramped, L2 roomier, but slower, and L3 spacious, but comparatively sluggish. When the data a CPU needs isn’t available in any of these places, it reaches for the RAM, which is much slower.

    You shouldn't pay too much attention to cache size, because it's hard to equate with real-world performance and there are more important factors to consider.
  • IPC: Even if you have two CPUs that have the same clock speed and same number of threads, if they’re from different companies, or built on different architectures from the same company, they will will produce different numbers of IPC (instructions per clock cycle). IPC is heavily dependent on the CPU's architecture, so chips from newer generations (ex: an 8th Gen Core i7 versus a 7th Gen Core i7) will be better than older ones.

    IPC is not usually listed as a spec and is usually measured through benchmark testing, so the best way to learn about it is to read reviews.

What do you need more: clock speed, cores or threads?

The answer to this question really depends on your needs. Higher clocks translate to quicker responsiveness and program load times (though RAM and storage speed is key there as well). Higher clock speeds also mean single-threaded tasks (like audio editing and certain older applications) can happen faster. Many popular games are still lightly threaded.

But many modern programs can take advantage of lots of cores and threads. If you do lots of multitasking or edit high-res videos, or do other complex, time-consuming CPU-heavy tasks, you should prioritize the number of cores. But for the vast majority of gamers and general-purpose computer users, a clock speed ranging from 3-4GHz with four to eight cores is plenty.

What socket does my motherboard need for this CPU?

Different processors require different socket types. If you already own a motherboard and don't want to replace it, you'll need to purchase a CPU that has the right socket type. Otherwise, you need to make sure that the motherboard you purchase is compatible with your new processor.

With its current-generation Ryzen and Athlon parts (barring Threadripper), AMD has adopted a single socket—AM4—and pledged support for that socket until 2020. That means you should, with a BIOS update, be able to put a first-generation Ryzen chip into second-generation (and possibly third-generation) Ryzen motherboard, and vice versa.

Intel, on the other hand, has a tendency in recent years not to support backward compatibility with its new chips and older motherboards, even if the socket is effectively the same. For instance, Intel’s socket LGA 1150 and 1151 differ by a single pin, and the version of 1551 designed specifically for 8th Generation Core chips is physically the same as that made for previous 6th and 7th Generation Core processors. But those older 1151-socket motherboards don’t work with newer 1151-socket CPUs, because (Intel says) the newer chips (which have more cores) have different power delivery subsystem needs.

This complexity is both frustrating from a future upgrade standpoint, and it means you have to buy a newer, more-expensive motherboard for a current-gen chip, even if a more-affordable previous-generation board has all the features you want.

Socket and Chipset Table


Intel MainstreamAMD MainstreamIntel HEDTAMD HEDT (Threadripper)
Current CPU SocketsLGA 1151AM4LGA 2066TR4
Compatible ChipsetsZ370
Z370
Q370
H370
B360
H310
X470
X370
B350
A320
X300
A300
X299





X399





Bottom Line

When choosing a CPU, first ask what you're going to do with it then see how much you can budget for it, after you've figured out how much you're spending on other components like your SSD, GPU, PSU and RAM. While processors are important, there's no point in pairing a high-speed chip with weak graphics (unless you aren’t a gamer) or a slow, spinning mechanical hard drive. While reading specs like clock speed and thread number is helpful, the best measure of a processor's performance comes from objective reviews like those we write here on Tom's Hardware.

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