THE ULTIMATE GUIDE TO CHOOSING A CPU



The CPU, which stands for Central Processing Unit, determines how much simultaneous data a computer can process and at what speed. It is the core component of what make a computer. It essentially the brain of your system.There are several factors to consider when choosing a CPU and we'll discuss them in detail here.

Last updated: 30/11/2020



1: What do you want your computer to do?

Getting this stage right is crucial as it can make or break your build.


If you want a computer that is used for light tasks (emails, web browsing, watching videos etc), you won't need a powerful CPU. If, however, you plan on using your PC as a workstation (working with large files, photo/video editing, You will need to spend a bit more on something more powerful.


For gamers, there are a lot of games out there that will play just fine on a low-end CPU. Think CS:GO, League of Legends and Rocket League, for example. Even high-end AAA titles don't utilise the additional core count of an expensive CPU, so if gaming is your bag, and you are not worried about using the system for much else, you can save money on the CPU and put it towards your graphics card instead.


2: Intel vs AMD





There are only two companies in the world who manufacture CPUs: Intel and AMD.


Intel are, by far, the more well known of the two, thanks to their extensive advertising campaigns over the years (anyone else remember the Blue Man Group adverts?!) They have also dominated the market for a very long time, with a huge market share.


AMD is not so well known and has had a chequered history. It's chips in 90's and 00's were not at all competitive with Intel's Pentium processors. They also tended to get quite hot and were not reliable. In the last few years, however, AMD has really turned things around. Their Ryzen series of CPU's offer amazing value and performance.


For gaming purposes, Intel is mostly still just ahead of AMD (but the gap is narrowing), so if frames-per-second are important to you, Intel should be your first choice. That is unless you can get hold of one of AMD's latest CPUs, the 5000 series, which is now the most dominant processor available.


AMD's Ryzen CPUs are the best value and perform well. They tend to offer more cores and threads (more on those shortly), which make them the CPU of choice for high-end workstations and video editing. If you want your PC to be an all-rounder, AMD is the way to go.

Naming Conventions:

There are lots of names, letters and numbers when you are looking at CPU's, but what do they all mean? Let's break it down.

Intel's Full Range:

Celeron: Basic entry level CPU. Able to cope with everyday tasks, but not much else.

Pentium: Once their flagship processor. Faster than Celeron at a reasonable price.

Core i3: Good budget performance CPU. Again, faster than Pentium with only a slight price increase.

Core i5: Solid performance CPU which offers Intel's best power to cost ratio. Much better than i3 in most respects and good for gaming.

Core i7: High performance CPU, ideal for non professional video editing / rendering and playing AAA games.

Core i9: The i9 is not for gamers as the cost is prohibitive for very little extra performance. Where this chip comes into its own is in professional workstations.


For the rest of the numbers and letters, let's take the i7 9700K as an example.


The first number, 9, shows you what generation the CPU is, so in this example we have a 9th Generation chip. The following numbers (700) show you the model of the CPU. The higher the number, the better the processor. Finally the letter denotes certain characteristics of the CPU:





AMD's Full Range:


Athalon: Budget CPU, superseded by Ryzen.

Ryzen 3: Budget CPU, and excellent value.

Ryzen 5: Mid-Range CPU, the sweet-spot for price vs performance. Solid all rounder and good for gaming.

Ryzen 7: Solid performance CPU, excellently priced. Good for non professional creatives and gaming.

Ryzen 9: High performance workstation CPU suitable for the heavy workloads, but still relatively price conscious. Direct competitor of the i9 series.

Threadripper: AMD’s flagship CPU. The threadripper will handle anything you throw at it, making it suitable for ultra workstations. Completely overkill for gaming.


As for naming conventions, let's take the Ryzen 5 3600XT as an example.


The first number, 3, shows you what generation the CPU is, so in this example we have a 3rd Generation chip. The following numbers (600) show you the model of the CPU. The higher the number, the better the processor.


There are fewer letters in AMD's naming convention:





3: What is your budget?

Linking to the 1st point, if you know the answer to the above, you can work out what proportion of your budget to assign to the CPU.


Obviously, the more money you have to spend means the better CPU options you have available. But that doesn't mean you should go out and buy an expensive one for the sake of it.


As a rough guide, consider the following budgets:

Basic tasks: £40-£80.

If all you are going to do is one thing at a time, then the lower end of this budget is perfect, but if you find yourself doing emails and browsing whilst listening to music, you are better off spending a little more on something like the Ryzen 3 3200G, which comes with integrated graphics processing, negating the need for a seperate graphics card.

Gaming: £120-£200.

For high-end gaming, you need to shoot for a mid-range Intel Core i5 or AMD Ryzen 5 CPU. As mentioned, the graphics card will be doing most of the grunt work, so over-spending here is pointless. The Ryzen 5 3600 is, in our opinion, the sweet spot for value vs performance. You could also consider the 3600x at the top end of the budget. If you want to go Intel, the i5 6900k is a great option.

Creative media work: £220-£320.

At this price range, AMD rules the roost and the Ryzen 7 series excels. If you need those extra cores for video editing or 3D modelling, you can't go wrong with the R7 3700x, which sits at the lower end of this budget, but is still a powerhouse. At the top end of this price range is the i7 9600k, which only has 8 threads vs the 3700x's 16, and has the same 3.6GHz base clock speed, but has more headroom for overclocking.

Workstation Powerhouse: £350+

There is potential to spend thousands in this price bracket. If you are rendering 4k/8k videos, or animating in 3D you will need a CPU with a lot of cores and threads. This is where AMD's Threadripper or Intel's Core X series comes in. These CPU's are monsters and will plough through heavy workloads with ease and help increase productivity. If you don't want to spend £1000, the your best option is the Ryzen 9 5950X (16 core/32 thread) or the R9 5900X (12 core/24 thread). These chips are still incredible and the best out there at the time of writing.

4: Cores and Threads

A CPU will come with a set number of cores. Cores are like separate processors that all sit on the same chip. Each core is capable of running a different process at the same time, therefore, the higher the number of cores the better that CPU is at multitasking.


Threads are slightly different to cores. They are not a physical component of a CPU but a virtual component that manages the tasks being done by the cores. It used to be that if you had 4 cores you would also have 4 threads, but a lot of modern CPUs utilise multithreading, meaning each core can handle two operations at the same time.


The number of cores is the thing to look out for when gaming. As mentioned, gaming doesn't require many cores as they put most of the strain on your graphics card. A CPU with 4 cores and 4 threads will cope with most games. Workstations need more cores to cope with the volume of processes being done simultaneously.


The number of cores isn't the only thing to consider. You do have to factor in the next point on the list.

5: Clock Speed

So you have your cores and threads figured out, but what about how fast your CPU is? This is the clock speed and is measured in megahertz (MHz) or gigahertz (GHz). This value indicates the number of tasks a CPU can perform every second. In other words, the larger the number, the faster the cores.


It does get complicated though. You would think a CPU with more cores than another would be the better option, but if the clock speed of the chip with fewer cores is greater, it may well be the better performer.


More complications incoming! Each CPU also has an IPC rating. This stands for instruction per clock and shows the number of tasks the CPU can complete in each clock cycle. The IPC rating is tied to the chip architecture. Currently AMD's Ryzen 3000 series uses their Zen 2 architecture which has a better IPC than Intel's Coffee Lake.

6: Overclocking

Overclocking is the process of increasing your CPU's clock speed. This makes your CPU faster meaning you can squeeze more performance out of it without paying for extra cores. This does produce more heat though, so you may also need to invest in a better CPU cooler.


If you are planning to overclock your CPU, this limits the options available to you. For Intel, you need to buy a CPU which has the letter k suffix, such as the i7 6700k. If it doesn't have a k at the end, then the CPU is locked at Intel's specified clock speed. These overclockable versions do come at a premium.


All modern AMD Ryzen CPUs have no such restrictions and can be overclocked, straight out of the box.

7: Getting the right socket

You need to make sure that the CPU you choose will be compatible with your motherboard. Your CPU is installed to the motherboard by fitting it into a socket. Unfortunately, not all sockets are the same so getting the right CPU/motherboard combo is essential.


Thankfully, AMD has adopted a single socket type for all its Ryzen and Athalon CPUs; the AM4 socket. This offers a good degree of flexibility as you are able to upgrade your CPU without replacing the motherboard.


Intel make things a little more complicated, as they have a tendency to not support backwards compatibility. This means you are likely to need a new motherboard if you are upgrading your Intel CPU.


Current Sockets and Compatible Chipsets





Now you know about sockets, we need to look at chipsets. Each motherboard has a specific chipset and you will need to make sure that the CPU you choose is compatible.


Take the AM4 socket, for example. At the time of writing, there are 9 different chipsets available. Some chipsets have more features and are built with more expensive components. Some chipsets have fewer features but are less expensive. I will go into more detail on chipsets in my motherboard guide.

8. Bottlenecking

CPU bottlenecking is a term used to describe when your CPU is restricting the performance of other components within your PC. The most common bottleneck is with the GPU.


If you have a high-end graphics card paired with a budget CPU, you will never get the full potential frame rate. Essentially, the CPU is not fast enough to keep up with all the frames being rendered by the GPU, so your graphics card never reaches 100% utilisation.


So, when considering your CPU choice, it's a good idea to have in mind what graphics card you are going to be using. If you are unsure, PC-Builds.com has a great bottleneck calulator, which will tell you exactly what level of bottleneck your chosen components will give you and the estimated fps of popular games.


Final Thoughts

There is a lot to take in here, so it's understandable that you may feel a little overwhelmed. If you'd like to talk through your options, feel free to get in touch with us. We'll do our best to help.