Welcome back to our guide to picking custom PC parts. Today we'll be covering the next most important part for any custom gaming PC: the processor. If you've made it this far in the series then a gold star for you because there's been a lot to learn - hopefully you've found it helpful so far! If you've not yet read part one or two, which cover the most important questions to ask before part picking and what to look for in a GPU, then hop over and have a read first! But without further ado, let's get into the...
The CPU, otherwise known as a Processor, or even more generally speaking, chip, is the part of your PC that, in the simplest sense, is responsible for doing maths and making decisions. It is constantly making calculations, following and giving instructions, and generally just all the basic things your computer needs doing in order to function properly. When it comes to gaming, the GPU does all of the heavy lifting, but the CPU does all of the serious thinking. You'll notice as we proceed, that a number of similar terms to those in our GPU post will start to come up, so hopefully you should be fairly comfortable with the initial concepts. In terms of picking a CPU, there are also only a few key specs to pay attention to, and this time we will use Intel's i5 10600K as an example, as well as AMD's Ryzen 5 3600XT:
First thing's first, don't let the Intel specs scare you - there's certainly a lot listed but most of it isn't of concern to us. You'll notice as you go through their various lines of processors that both companies also use multiple letters that they attach to the processors' names which can sometimes be quite confusing too (I'll break down the naming schemes later, so don't worry about that just yet). For the time being, take a closer look and compare it to the AMD specs. AMD tend to keep it simpler, but ultimately everything listed in the AMD specs is also in the Intel specs somewhere, you just have to look a little harder. To lend a hand, here's an edited version of the Intel list, indicating the specs we're interested in:
As you'll notice, there are a number of things we want to pay attention to, but when it comes to performance specifically, much like the GPU, there are only 3 key specs we need to pay attention to; the first is the number of Cores and Threads, sometimes written as Xc/Xt, in this case 6c/12t for both processors. The second is Base Frequency/Clock, and Max Turbo Frequency/Max Boost Clock, which are measured in GHz. And the third is Lithography/CMOS, which is always represented as Xnm, in this case 14nm.
There are a few other specs we need to consider here which, although they do not directly affect performance, are very important for compatibility with your other components. They are the Supported Socket (or Package), and three of the Memory Specifications; Speed - the ideal speed of your System Memory for that specific processor; Type - which kind of Memory it supports, indicated as DDRX (where X is a number); and Channels - which for our purposes, only ever needs to be 2.
CPU - Central Processing Unit; sometimes referred to as the Processor, or simply chip, the CPU is the brains behind the operation.
Cores/Threads - Any CPU has a set number of Cores. It is the cores of a CPU which provide its processing capabilities. These cores run at different speeds, also known as clocks or frequencies (covered in the next point below) and each has its own 'thread.' Many modern CPUs can perform what's known as 'multithreading,' (or hyperthreading for Intel products) where a single core will perform two tasks simultaneously in order to increase its processing efficiency in certain scenarios. This is why, more often than not, a CPU will have twice as many threads as it does cores. On the rare chance that you come across a CPU which has the same number of threads as it does cores (and it will be rare in the present CPU landscape), then this particular CPU will not be able to perform multithreading.
When it comes to gaming, multithreading has not yet been widely adopted (though this will likely change in the future), and so better performance in games tends to come from higher clock speeds.
Frequencies/Clocks - Much like GPUs, CPU cores run at certain speeds. These speeds are measured in GHz and refers to how quickly the processor can do what it's got to do - the base clock usually refers to the speed that the cores work whilst idling and performing light workloads, whilst the boost/turbo clock refers to the fastest speed at which it can retrieve, process, and deliver data to where it needs to be, which usually happens under more demanding workloads, such as gaming with high refresh rates. This means that generally, the faster the CPU, the better your PC will perform in gaming, as the rest of your hardware doesn't have to wait on the CPU to ferry all the data between your hardware and monitor.
Generally speaking, as core-count increases, frequency tends to decrease and this is for two reasons; firstly, with more cores comes more raw processing power, as tasks can be more evenly distributed, and therefore faster speeds are less necessary. And secondly, the faster the cores work and the more power they draw, the hotter they become - as you pack more cores into a single CPU, the density of those cores increases, thus so does the heat it generates, which eventually means the processor becomes less efficient. As such, having CPUs with many cores running extremely fast is not particularly viable, or desirable. As mentioned previously, this means that, when building a machine for gaming, the bias for CPU specs should lean towards higher clock speeds, rather than core-count.
Lithography/CMOS - To keep it simple, this refers to how dense the architecture of the processor is and is measured in Nanometres (nm), with smaller numbers indicating higher density and therefore, better overall performance as a result of decreased latency in communication between the cores of the chip. Intel are currently using 14nm and 10nm, whilst AMD have already made the move to 7nm.
Like CUDA Cores and Stream Processors, this can be used as a rough guideline as to how well the processor will perform - in particular, how fast it actually is when comparing to other similar processors of the same and older generations, and by the same company.
For example, AMD have two particular processors, the Ryzen 5 1600 and the Ryzen 5 1600AF - at first glance, these two processors are practically indistinguishable from one another; both have 6 cores and 12 threads with clock speeds of 3.4GHz up to 3.6GHz. They also share 16MB of L3 cache, an estimated power draw of 65W and have a maximum operational temperature of 95°C. But the 1600AF will almost always outperform the non-AF variant. Why? Because the non-AF variant is built upon 14nm, whereas the AF is a refreshed design built on 12nm, using their improved Zen+ architecture. So even though their specs are otherwise the same, the AF variant will still be faster and more efficient as a direct result of an improved lithography/CMOS and architecture.
Fortunately, most modern processors of the same generation are usually on the same lithography/CMOS and architecture, so 99% of the time, it's something you won't need to worry about. But it's one of those niches worth being aware of, all the same.
As a rule of thumb, when it comes to gaming and CPUs, and much like GPUs, higher clock speeds mean better frame rates in games which means a smoother visual experience - for gaming, around 4.0GHz is the sweet spot for pricing and performance, but of course, if you can go higher, then the results will follow. You should also think about what resolution you're intending to play at, as the higher the resolution, the more benefit to having additional cores. We always recommend a minimum of 4 cores when starting at 1080p resolution, with 6-8 as minimum at 1440p, depending on the graphics settings you'd like to play at. 6-8 is usually ample for most, but if you're wanting to push for smooth 4K, aside from an ungodly graphics card (which you don't want to bottleneck with a low-end CPU), 10-12 cores in your CPU are a must. Outside of these considerations though, the graphics card is doing the majority of the work for gaming, so you should spend most of your time and money on the ideal GPU. For gaming PCs, we usually recommend a rough 2:1 split for your budget, with your graphics card being around twice the price of the CPU you purchase.
When it comes to figuring out which CPU is best for you though, just like GPUs, don't rely on the paper specs alone; research and benchmarks will always be your go-to. Do your reading, listening and watching, and remember that we always have experts on hand to help you find the perfect components for your dream Custom PC. Another thing to consider here (and you may have noticed a theme), is to go back to your answer to question one - as mentioned previously, if you happen to play a lot of very casual games like Point and Click, 2D Puzzlers and Platformers, or Visual Novels, check what the recommended specs for these games are. These sorts of titles tend to be significantly less demanding than other games and genres, and may not even require discrete graphics, instead capable of running on integrated graphics.
Put simply, some models of CPU are specially designed to be capable of behaving as both the CPU and GPU, albeit with very limited scope when it comes to the graphics side of things (compared to dedicated graphics). These types of processor have come a long way in the last 5 years though, with AMD spearheading the technological advances, coining the name APU (Accelerated Processing Unit) for their line of processors using integrated graphics. Historically speaking, APUs would generally only appear in the likes of mobile devices, such as laptops, tablets and mobile phones, providing the necessary means to power their displays, videos and simplistic games at simple, low-refresh resolutions. But with how far these processors have come, more recently, some gamers (especially those looking to custom-build cool, quiet ITX PCs) have been swayed towards the likes of an APU. The new 4000 series of APUs by AMD (currently only available to OEMs), which utilise the power and efficiency of their Zen 2 architecture and pair it with their new Radeon Graphics, will offer some ridiculously powerful processors to the enthusiast market; the most powerful of these chips, the 4700G, offering 8c/16t at up to 4.4GHz, allowing you to 'stream your favourite shows in vibrant 4K, HDR...' and giving you 'smooth 1080P gaming right out of the box... [with an] easy path to future upgrades like graphics cards for HD+ gaming when you're ready...' - AMD's marketing, but certainly not hyperbole.
But how exactly do you identify a processor with integrated graphics? Well, as promised, it's all in the naming scheme (as well as the spec list of course), so allow me to give you a run down on how Intel and AMD have named their current CPU line ups.
Starting with AMD (because it's a bit simpler), the naming structure is as follows:
First up is the series name, in this case, Ryzen. This will vary between generations and architectures (other AMD series examples would include Athlon and Athlon Gold, Threadripper etc.), but for gamers, Ryzen will likely be the series of choice for the foreseeable future.
Next is a number which will be either 3, 5, 7 or 9 which acts as a quick indicator of how far up in the series a processor is. The higher the number, the more powerful the processor.
The next number we can break down into two parts; the first digit (3) will indicate which generation it fits into if there are multiple generations across a given series. In this case it's a 3rd generation, or 3000 series, Ryzen. The second number (600) acts as a kind of sub-set of the first, indicating how powerful it is in relation to other processors in the same overarching category i.e. a Ryzen 5 3700 is more powerful than the Ryzen 5 3600.
And lastly, we have the letter suffixes - these are fairly straightforward again, simply indicating how powerful the processor is compared to other models of the same name. For example, the 3600XT is ever so slightly more powerful than the 3600X which, in turn, is more powerful than the 3600.
The only real exception to this rule is when you come across a G, which very simply, stands for Graphics and therefore indicates that this particular processor has integrated graphics, as is the case with the Ryzen 5 3400G.
Intel's naming scheme is pretty much identical, though, unlike AMD where most of their letters just mean "even more powerful," Intel's can become quite convoluted. Each letter means something very different, and there are quite a few of them (17 to be precise). But fortunately, when it comes to gaming, you'll only have to know a handful of them (thank goodness).
Just like AMD, first up is the name which refers to the series; Intel Core. Other examples include Pentium and Celeron, but these are mainly for servers and workstations.
Next is the primary identifier for how powerful it is, starting at an i3, and progressing through i5, i7, and lastly, the i9.
Then we have the generational indicator again (10), this time highlighting that this is an Intel 10th Gen, or 10000 series processor, followed by the sub-set identifier - an i5 10600K, for example, being more powerful than the i5 10400.
And finally, any letter suffixes to identify specific features:
No letter or G - Vanilla Intel processors (including their basic integrated graphics for troubleshooting)
F - No integrated graphics, requires discrete
K - Unlocked: no artificial caps on the chip's performance, allowing for enthusiasts to overclock
S - Special edition, usually meaning marginally better than the original variant, such as in the case of the i9 9900KS
And that's pretty much all there is to it... hopefully a tad less confusing now...
Naming schemes out of the way, let's continue our CPU considerations by taking a look at those other specs we mentioned in passing earlier, namely those that will affect compatibility and optimum performance.
Less thrilling than performance specs but undeniably important to any custom-build, there are a handful of other technicalities you'll need to take note of when choosing your processor, be it CPU or APU. These are as follows:
Socket/Package - Any processor you choose is a certain size with a certain pin layout, and these pins need to slot into a socket on your motherboard. For each series of processor, the pins will do different things, dependent on the design of that particular chip, or series of chips, and therefore there will be a matching socket type in a series of motherboards, specially made for that line of processors. Whenever you choose a processor, be sure to check what socket/package type the CPU is, and make a note for later when you start looking at which motherboard you'd like to pair it with.
System Memory Specification/Speed/Frequency - This simply refers to your RAM, which we'll discuss in a later post. Think of this as the ideal speed that your RAM should be operating at. At the least, you should avoid going lower than this figure, but you can go higher. This is just the recommended speed that the manufacturer would aim to use for the stock experience with their processor. More often than not with Intel, matching this number isn't too much of an issue and going higher can actually yield improved performance. But with AMD processors especially, try to match it as best as possible and avoid going higher in particular, since the most recent AMD processors (Zen 2, 3000 series chips & Zen 3, 5000 series chips) currently don't benefit from speeds faster than 3400-3600MHz (meaning you'll pay extra for no reason).
Memory Type - This indicates the type of memory the processor can support up to. It's written as DDRX (where X is a number) and currently the most common type available to the desktop enthusiast is DDR4.
Memory Channels - This indicates how many sticks of RAM the processor can utilise. For our purposes, this number only ever needs to be 2, which tells us that we can have up to four sticks of RAM on our motherboard for a processor to make use of.
And that's all you really need to be aware of. A lot of info I know, but in summary; for gaming, you'll likely want to choose a processor with 6-8 cores and a decent clock speed up to at least 4.0GHz. You need to make sure that you note the socket/package type so you don't end up with an incompatible motherboard, and if you choose AMD's third gen or fourth gen Ryzen processors, then be sure your RAM is no higher than 3400-3600MHz (unless you just have money to burn).
Hopefully this has been an informative piece that's given you some new knowledge or a better understanding of what a processor is and how it works, and even better if you've gained some confidence in understanding the specs to help inform your decision on what CPU to pick next.
Join us in part four where we'll be continuing this mini-series with an in-depth article on the third most important part of your custom PC: the motherboard. See you there!
Posted in Guides & How To
Published on 29 Sep 2020
Last updated on 13 Jan 2021