Trying to figure out the best CPU for your next PC upgrade or DIY build? With apologies to Robert Frost, it's the classic two roads that parted in the wood—if the wood were a shopping-results page at Newegg or Amazon, and the road kept dividing endlessly.
Two roads, splitting to four roads.
Then eight.
(Better leave breadcrumbs.)
Indeed, buying a CPU is akin to a whole forest of decision trees.
Which of the two big chip makers should you go with: AMD, or Intel? Are you trying to maximize speed, or value? Does the maximum number of cores matter more, or does clock speed? Are you upgrading, or building a whole new PC? Are you gaming? Not gaming? Still awake?
All of these questions are crucial in landing the right chip, and what that means: No single CPU is the absolute best across the board for all users, assuming money matters.
It's possible to objectively measure CPU performance across a range of applications and usage cases, and if you're not bound by mere-mortal concerns such as a budget, it's easy enough to get a pretty good idea of what "best" means.
(Spoiler: Intel Core i9-10980XE Extreme Edition or AMD Ryzen Threadripper 3990X, one or four grand, respectively.)
But just because these, the CPU equivalents of maximum-horsepower V12 or V16 engines, exist doesn't make them the right pick for every shopper, or even most shoppers.
Other concerns—cost, energy consumption, the kinds of roads (read: tasks) you drive every day—matter just as much as out-and-out muscle.
The best way to look at a CPU buy is to take the considerations in a logical order, which will narrow the field as you make your choices.
So, the first big one: Are you upgrading a PC, or building a new one from scratch?
Consideration No.
1: Upgrade, or New Build?
Answering this question will set you on a narrow path or a broad one.
If you're upgrading an existing desktop PC, your CPU upgrade options, by definition, will be limited: by the architecture, socket, and compatibility of the motherboard installed in the PC.
If you are willing to swap out the motherboard to step up to a newer or more powerful class of CPU, that project becomes, in effect, building your own PC.
That's because a motherboard upgrade requires at least partial system disassembly, and sometimes replacing further parts to make the upgrade work.
Often, "In-Place" Upgrades Are a Waste of Time
In most cases, upgrading to another chip that works in the same socket as the one in your PC will have limited upside.
In recent years, chip sockets or chipsets are only compatible for a generation or two of CPU, and once the year or two passes, the next platform is no longer compatible with the ones that came before.
(Late-model mainstream AMD CPUs, on AMD's "AM4" socket, have broken that cycle for the moment.
More on that later.) What that means: Unless you're upgrading from a low-end chip early in a platform's lifecycle to a high-end CPU at the very end, you're not likely to gain too much from an in-place CPU upgrade on a dead-end platform.
In speaking of CPU lifecycles, the key consideration when you're looking to upgrade on an existing motherboard is socket compatibility (that is, the receptacle into which you seat your new CPU).
We can't account for every aged or ancient socket that your PC upgrade might involve—there are just too many—but we can say this: It's seldom worth upgrading a CPU on a dead-end socket unless you've gotten a stellar deal on the new chip, and you're making a clear jump forward in core/thread count, or raw clock speed at the same core/thread count, from the old chip to the new.
So, Wait...How Do I Know What's a Dead End?
As a quick guide, here are our rough recommendations for upgrades if you're on a given platform.
Googling the name of the CPU in your system and selecting the spec page on AMD's or Intel's site will divulge what "socket" the CPU is on...
Again, we reiterate: This is a rough guide! There are edge cases on every line.
If, say, you're getting an Intel Core i7-6700K off Craigslist in exchange for $50 and a six-pack of Samuel Adams, meaning to replace a Core i3 on that platform, by all means, go for it.
But in most cases, if you have a midrange or better CPU on a given dead-end platform, unless you're getting a new chip cheaply, you'll get more bang for your buck buying a new motherboard and CPU on a current platform.
After all, a new board on Intel's or AMD's mainstream platforms can set you back as little as $50.
(Of course, if your older system is still on DDR2 or DDR3 memory, you'll need new RAM, too; both Intel and AMD have moved to DDR4 on all of their current consumer platforms.)
Buying Basics: Four Key Concepts to Know About CPUs
Let's take a quick look at some basic specs you need to understand before digging into Intel's and AMD's lines.
CORE COUNT. It's a gross oversimplification, but think of core count like engine cylinders; more cores generally indicate more power, all else being equal.
(Properly written software can use more than one core to process parts of a task at a time.)
Of course, all else is seldom equal, and comparing core count is really meaningful only within a given CPU line and in the same generation of that line.
That said, more cores are generally better, within reason.
If the software you use is multithreaded (this especially applies to modern content-creation and -editing packages for graphics and video), more cores will help.
And some demanding PC games require a certain core or thread count, usually a minimum of four.
In descriptions of CPUs, you may see the core/thread count in a sort of shorthand (we'll do so below), for example, 8C/16T, meaning eight cores and 16 threads.
MULTITHREADING. Intel and AMD CPUs support multithreading in certain of their chips.
In a nutshell, multithreading allows your PC to run two discrete processing assignments, or threads, on each core.
This doubles the simultaneous processing potential, assuming that the software and operating system can leverage it.
Intel calls this trait Hyper-Threading (HT), while in the AMD world, it's referred to by the generic term SMT, for symmetric multithreading.
Practically speaking, it is the same thing.
For CPU-intensive tasks such as video rendering, support for HT/SMT is a very good thing.
Note that Intel, with its 9th Generation mainstream Core CPUs for desktops, pushed HT further up its stack than ever before.
(Only the Core i9 chips supported HT.) That has changed with Intel's newest 10th Generation Core desktop chips; HT has returned to Core i3, i5, and i7 chips.
SMT goes up and down the mainstream chips in AMD's Ryzen desktop line.
BASE CLOCK, BOOST CLOCK.
Measured in gigahertz (GHz), these are two of the primary specs for any given CPU, but they require a bit of context.
The base clock is a multiple of the system's low-level clock and the CPU multiplier (which may be manually tweakable; more about that in a moment) and is the default speed at which the chip cores run.
The boost clock is a higher ceiling at which one or more of the cores can run when the task demands it, and when the system's thermal conditions allow.
Depending on the software involved, the CPU cooling hardware, and the traits of the CPU itself and its motherboard, an accelerated clock rate up to the boost rate might kick in on some or all of the system's cores, sometimes varying at any given time from core to core.
Boost clock is not always evenly spread across all cores.
Like with core count, these numbers are telling only within a given processor family; a 3.5GHz Intel Core X-Series chip and a 4GHz AMD Ryzen mainstream chip are not directly comparable on the basis of clocks alone.
This is where formal benchmarking and labs-based reviews like ours come to the fore.
LOCKED VERSUS UNLOCKED. A chip that's "unlocked" for overclocking has its clock multiplier open for tweaking within the BIOS or in-OS overclocking software.
The multiplier is locked down on other chips.
We've detailed the overclockability of each line below, but in sum: Intel Core X-Series, AMD Ryzen, and AMD Ryzen Threadripper chips are unlocked, while Intel's mainstream Cores are a mix, but mostly locked.
More about overclocking, again, near the end of this guide.
So, Which Intel or AMD Processor Line to Choose?
Assuming you are staying on a given motherboard, your CPU choices will by definition be limited.
But if you're open to all of the current CPU platforms, you need weigh the various AMD and Intel chip families.
With that in mind, let's take a look, in turn, at each of the lines that are relevant today for PC builders and upgraders.
8th, 9th, or 10th Generation Core: Intel's Mainstream Choices
At this early-2021 writing, Intel has several generations of its mainstream Celeron, Pentium, and Core i3/i5/i7/i9 CPUs on the market at the same time.
All but the very latest make use of a motherboard CPU socket called Socket 1151.
Socket 1151 is physically compatible with chips from the Celeron to the Core i9 across the 7th Generation ("Kaby Lake"), 8th Generation ("Coffee Lake"), and 9th Generation ("Coffee Lake Refresh") platforms.
The now end-of-life 6th Generation ("Skylake") processors also live on this socket.
Note we emphasized "physically." Chips from any of these generations will fit in any Socket 1151-equipped motherboard.
But, that said, not every 1151-class chip will work with every Socket 1151 motherboard.
You'll also need to factor in the onboard chipset, the motherboard's governing silicon.
For example, 9th Generation CPUs like the Intel Core i9-9900K won't work with most older Socket 1151 boards; you'll need a board that supports the Z390 chipset.
(The i9-9900K and its limited-edition variant the i9-9900KS are the peak chips in this generation, with eight cores and 16 threads.)
Untangling chip, board, and chipset compatibility can be really tricky with these chips, and you will often see four or five chipsets that work with a given chip generation, targeting different price strata and use cases.
So you want to check the specs carefully to make sure that the motherboard you have or are considering supports the exact—and we do mean exact—chip you're looking at.
Motherboard makers usually provide detailed CPU compatibility lists for a given board.
Heed them.
For example, the Z390, Z370, B365, B360, H370, and H310 chipsets all are relevant for the 8th and 9th generations of Intel CPUs, but you'll want to check the compatibility lists.
The Z chipsets are meant for overclockers and tweakers (paired with an unlocked CPU), the H370 is for mainstream users not intending to overclock, the B360 and B365 are more budget-level chipsets (generally found on boards with fewer features and ports), and the H310 is the most stripped-down of all.
This Z/B/H letter scheme has held for several generations now.
As we alluded to earlier, one thing to note with the 9th Generation Intel mainstream CPUs is that only the highest-end support the doubling of processing threads via Hyper-Threading.
This matters if you tend to use applications for content creation, rendering, and other intensive operations that make use of all the threads you can get.
If you've owned earlier Core i7 chips with HT, don't assume it's supported on recent chips.
Check.
That changed with the 10th Generation.
Dubbed "Comet Lake-S" and headed by the Core i9-10900K, this new Intel line has HT up and down the stack.
It also uses a new socket, LGA 1200, which is incompatible with all else that came before.
The chipsets relevant to this line use the same Z/B/H scheme: Z490 (high end), B460 (mainstream), and H410 (budget).
These boards and chips hit the market in mid-2020.
The 11th Generation has been partially disclosed but is not slated to hit the market until March 2021; dubbed "Rocket Lake-S," these chips will bring PCI Express 4.0 support to Intel-based desktops for the first time.
More on them soon.
In terms of nomenclature, the performance pecking order within each Intel chip generation is Celeron (generally slowest), followed by Pentium, Core i3, Core i5, and Core i7, and finally, Core i9 CPUs, the last introduced to Intel's mainstream Socket 1151 platform with its 9th Generation family.
(The very first Core i9 chips debuted in 2017 on Intel's Core X-Series; more about them below.) Within each of these chip classes are CPUs with modest differences in clocking, as well as CPUs with overclockable versus locked-down multipliers.
(The overclockable chips end in "K" or "KF"; they are mainly Core i5, i7, and i9.)
One note that even those familiar with Intel's CPU lines over the years ought to know has to do with integrated graphics.
Traditionally, Intel's mainstream CPUs have incorporated on-chip video acceleration, under the name Intel HD Graphics, UHD Graphics, or Iris Graphics.
(These kinds of on-die graphics solutions are also referred to as "integrated graphics processors," or IGPs.) That means, assuming the motherboard has the appropriate video outputs, that you can use the IGP as...
