A computer buyer’s guide: The processor

And so we’ve reached the third chapter of our guide on how to buy a new computer. This time we’re going to discuss what processor you should get in order to achieve the perfect balance between performance and money spent on it. The processor is arguably the most important component in your PC because it basically determines how fast and responsive your computer is going to be. You’re going to get a better experience with a good processor paired with not-so-stellar components, than with high-end components and a crappy processor.

What is a processor?

An Intel Core i7 Extreme processor, one of the most powerful (and expensive) CPUs you can buy
An Intel Core i7 Extreme processor, one of the most powerful (and expensive) CPUs you can buy

The terms processor and CPU (an acronym for Central Processing Unit) are used interchangeably in the context of PC building. While they don’t mean exactly the same thing, for the sake of simplicity we’re going to pretend that they do. Please note that AMD calls their processors “APUs”, which stands for Accelerated Processing Unit. They call them “Accelerated” because they include quite capable integrated graphics. We’ll discuss about integrated graphics in another article.

Every processor in existence is built around some core principles that define how it works and how the programmers can send instructions to it. These principles are collectively known as the architecture of that processor. By far, the most common architecture in desktop and laptop computers is x86. We’re going to ignore other architectures because they’re so uncommon that you’d be hard-pressed to find a computer that uses them and because software for them is hard to find. Not to mention, the two major operating systems only run on x86.

A while back, choosing the best processor basically meant comparing its clock speeds, expressed in megahertz or gigahertz. Unfortunately for all of us, this is no longer the case, because processors have evolved and started including additional technologies that improve performance, security, or power efficiency. Raw clock speeds can still be useful when comparing processors from the same family, however.

Today, if you’re getting a new computer, you will always get either an Intel or AMD processor, which you can tell apart by the sticker found on its front or near the keyboard if you’re getting a notebook. As a rule of thumb, Intel processors are generally more expensive, but slightly more powerful than their AMD counterparts, whereas AMD products are cheaper and provide a better bang for the buck. This has to do with how the two companies design their processors.

To keep it simple, when AMD designed its latest line of processors based on the Bulldozer microarchitecture, it hoped that software developers followed suit to develop programs better optimized for their own design. That didn’t happen and current software takes better advantage of Intel configurations. It was such a hard blow for AMD that its new line of CPUs, to be released in 2017, will be more similar to what Intel is doing, at least judging from how the press is reporting its development.

Features to look for

Turbo Boost and SpeedStep

One of the features you should look for in a processor is if it implements Turbo Boost (Turbo Core on AMD CPUs), a technology that dynamically increases your processor’s clock speed when it needs more power and power consumption is less important. In laptops, Turbo frequencies are usually much higher than standard clock speeds, which helps during boot and when opening an application. Because of how laptops dissipate heat, however, their processors cannot run on Turbo mode for prolonged periods of time. On desktop processors, Turbo frequencies are usually much lower, but they can run for longer in Turbo mode.

Related to Turbo Boost is SpeedStep (for Intel processors) and Power Tune (for AMD ones), a technology that predated Turbo Boost by a couple of years and that dynamically lowers a processor’s clock speed when idling, helping with power saving.

Hyper Threading

Hyper Threading is another feature that is nice to have, if you can afford to spend extra money on a Core i7 processor. It is Intel’s implementation of Simultaneous Multi Threading (SMT), that schedules running applications intelligently so that the operating system see two virtual cores per physical core on the CPU, allowing it to run more threads at the same time. This is quite a technical topic and I don’t expect everyone to fully understand how it works, but suffice it to say that with more cores (either physical or virtual) the CPU can do more things at the same time, thus improving performance in certain workloads. AMD CPUs implement SMT in a slightly different way, which theoretically gives them an edge on different types of workloads.

Mobile processors have a catch 22: they’re built around the idea of providing sufficient performance without being too power-hungry, lest they become too taxing on your laptop’s battery. This is where Intel processors clearly have an edge over AMD offerings: you will be hard-pressed to find any ultraportable or convertible with an AMD processor, because they’re much more power hungry. Laptop buyers are better off with an Intel processor, or they may end up getting a computer that drains the battery too quickly.

Depending on your workloads, Hyper Threading can actually be less beneficial than a higher clock speed. In particular, workloads that rely entirely on single threads will likely be slower with Hyper Threading on, as shown in this article.

The truth, however, is that you’re not very likely to see much difference between AMD and Intel processors in your day-to-day work, so my suggestion is to purchase what you can reasonably afford without breaking the bank.

Intel processors

Here is a brief summary of Intel processor families. The column Technologies supported refers to those we discussed in this article. They may support other types of technologies that I didn’t think were worth mentioning for the sake of keeping this article as approachable as possible. You can find more information about Intel processors at ark.intel.com.

Xeon processors are made for workstations and servers, but low-end E3 models are compatible with normal desktop sockets (although they require specialised motherboards). They do not come with integrated graphics, so you’ll need a dedicated graphics card if you want to get any video output. The two notable models mentioned here sell for prices comparable to those of Core i5 processors, yet they provide performance levels similar to that of i7s.

Family Technologies supported Notable models Short description
Celeron SpeedStep N/A Intel’s entry-level processors. They’re much cheaper than other families and are generally not worth getting, because chances are they’re already too slow.
Pentium SpeedStep Pentium G3258 Pentiums are more expensive than Celerons and generally slightly better at computing tasks. They’re aimed at inexpensive desktops and laptops that provide acceptable levels of performance. The Pentium G3258 is particular because it allows overclocking.
Core i3 SpeedStep

Hyper Threading

T models (ex. i3 6100T)

U models

Core i3 processors come with Hyper Threading and are considered decent processors for the money. T models have low power consumptions, which can prove useful for low-power, low-noise machines.

U models (where the U stands for ultra-low voltage) are commonly found on ultraportables and consume very little power.

Core i5 SpeedStep

Turbo Boost

Hyper Threading (on mobile models only)

T models

i5 6400

K models

U models

This family proves very popular with gamers thanks to their great price to performance ratio. All desktop core i5 have four cores, whereas mobile models have two hyper threaded cores. Depending on your workloads (for example, if you’re a translator) these are the processors to get. K models are also overclockable, if you want to go that route.
Core i7 SpeedStep

Turbo Boost

Hyper Threading

T models

K models

U models

 

Core i7s are basically Core i5s with Hyper Threading enabled. The law of diminishing returns is in full swing here: By buying one, you’re getting actually less for your money.
Xeon E3, E5, E7 SpeedStep

Turbo Boost

Hyper Threading

Xeon E3-1240 v5

Xeon E3-1231 v3

Atom SpeedStep N/A Atom processors consume very little power. They’re usually found on mobile devices and some motherboards designed for use in home servers.

AMD processors

Here is a comparison of AMD processor families. You can find more information about AMD processors at products.amd.com:

X4s are more powerful but draw a lot more power than simple Athlons. It should also be noted that Athlon X4s have no integrated graphics. A10 APUs are A8s on steroids: the main difference between them is a higher clock speed (and, in some cases, power consumption) and more advanced graphics capabilities. Opteron processors are meant for use on servers should generally be ignored in a work computer.

Family Technologies supported Notable models Short description
Sempron N/A N/A Sempron processors are low-power models that prove useful in home servers and other computers that require small amounts of power. They’re not very powerful and are not recommended for an office computer.
Athlon N/A Athlon 5370 Athlon processors are a step up from Sempron models, with whom they share the same power consumption, but provide better performance. They’re quite good for budget computers.
Athlon X4 Turbo Core N/A Athlon X4 shouldn’t be confused with Athlon models.
A6 Turbo Core N/A A6 APUs represent today’s entry-level AMD CPUs. They’re all dual-core processors with four graphics cores.
A8 Turbo Core

Power Tune

A8-7600 A8 processors are a step up from A6 CPUs. Not only do they support Power Tune and Turbo Core, but they also have 4 cores and better integrated graphics.
A10 Turbo Core

Power Tune

FX Turbo Core

Power Tune

FX 8350 FX processors are the most powerful desktop models AMD has to offer. NOTE: FX processors do not have integrated graphics capabilities.
Opteron Turbo Core

Power Tune

About Andrea Luciano Damico 110 Articles
Andrea Luciano Damico is a freelance translator from Italy. Among his interests are linguistics, technology, video games, and generally being a chill guy. He runs Let's Translate.it and Tech4Freelancers.net.