How to choose the right processor for your needs
Whether it’s for a budget PC, gaming superpower or anything in between, choosing a CPU for your needs isn’t straightforward. We help you narrow down your choices
Processors are far more complicated than they used to be. You can’t just pick a type and look at the clock speed to find the best one for you; instead, you need to closely examine each processor’s capabilities and features so you can find the right one for you.
Core drill
One of the most important things about a processor is the number of cores that it has, and that’s for two reasons. First, demanding applications can use multiple cores to speed up tasks; the more cores you have, the better.
Second, as each core is a CPU in its own right, having multiple cores means that there’s more processing power to share around. That’s very important, as you can have some cores dealing with background tasks while the spare processing power goes into a tougher job, all without you noticing your CPU slowing down.
Beyond core count, there’s the thread count. Both Intel and AMD employ technology that lets a core run two threads (or tasks) at the same time. You don’t quite get double the performance, but there’s a notable speed boost.
Slightly complicating things is Intel’s new architecture, which introduces CPUs that have highperformance P-cores (with HyperThreading, for double the thread count) and efficient E-cores (no Hyper-Threading). The big P-cores take care of the tough tasks, while the E-cores more efficiently deal with background tasks. The combination of the two is a potent one.
Before you rush out and buy the processor with the highest number of cores (or threads), be careful. The highest-end processors are really only for people doing tough jobs, such as rendering 3D models, CAD and video editing. In general, we’d say that a quad-core processor is a bare minimum for a new PC, but six cores are better; eight cores are good for a mid-range machine, but go higher if you need something that will handle more demanding jobs.
Clock watching
A processor’s clock is a measurement of its speed: the higher the clock speed, the more instructions can be performed in a given time period. Looking at clock speeds isn’t quite as simple as that, however.
First, processors do not run at just one speed. Instead, they have a base speed and a boost speed. The base speed helps the processor run cool, quiet and efficiently when it doesn’t need more power; the boost speed lets the processor work as fast as it can.
Note that maximum boost speeds are available only when a processor has enough thermal headroom; in other words, when it’s as cool as it needs to be. That means you may get different results from the same CPU depending on the cooler used.
Higher clock speeds generally have more of an impact on single-threaded tasks: image editing, office software and (typically) gaming will all benefit from higher clock speeds. Where there’s a more difficult multithreaded job, such as video encoding, a CPU with more cores but a lower clock speed can do a better job than a “faster” CPU with fewer cores.
Talkin’ ’bout generation
To further add complexity, you also need to look at a processor’s generation. With each new range of processors, Intel and AMD aim to make them more efficient. Typically, that’s by increasing the number of instructions per clock: in short, a CPU can do more per clock than an older generation.
We’re currently on Intel’s 12th generation Core architecture, called Alder Lake, which was released in November 2021. All the AMD chips on test this month use the company’s Zen 3 architecture, which was announced in November 2020. Zen 4 is expected later this year. As it stands, the current Intel processors are more efficient per core than AMD’s.
Note that maximum boost speeds are available only when a processor has enough thermal headroom
Cache points
A few other things are important to look at. First, there’s the cache, which sits between the CPU and memory. It comes in three types: L1, L2 and L3. The more cache you have, the fewer times your processor has to wait for requests to go to slower system memory. Higher cache amounts can make a big impact in games: that’s the reason why the Ryzen 7 5800X3D, with its 92MB of cache, excels in gaming benchmarks.
Also look at the Thermal Design Power (TDP) rating of a chip. Smaller chips with a 65W TDP can be cooled by a stock cooler or even used in a
slimline mini-ITX case. Chips that have 100W TDP or higher will need even more powerful cooling (air or water) to dissipate heat when the CPU is running at full pelt.
Few chips ship with a stock cooler any more, but we recommend buying your own choice of cooler anyway, not least because third-party models are often quieter than the stock ones.
Although the Intel processors we’ve reviewed all have integrated graphics, you can buy versions that drop integrated graphics to save cash. None of the AMD models on test has graphics, but you can expect similar performance if you look for the same model name but with a “G” at the end (for example, Ryzen 5 5500G). If you want to build a budget PC and don’t care about gaming, integrated graphics are the way to go, although you can buy a basic graphics card that’s no good for games for under
£30 if you need this.
Look out for the flags at the end of a processor’s name. With Intel, “K” models have unlocked multipliers, which means you can tweak the boost speed to make them run faster. This is ideal for those with excellent cooling in their PCs, as they can push a CPU faster than its default speeds. AMD has a similar “X” tag for its unlocked processors.
Intel also has “F” chips, which ditch the integrated graphics (as mentioned above), usually bringing the price down by around £30. You can buy processors with both (“KF”): unlocked and without graphics.
Motherboards and sockets
You’re often not only buying a CPU but also a motherboard to fit your processor. With the current Intel chips, you have to buy a new motherboard that supports the new LGA-1700 socket. It’s larger than the older socket, so most old coolers won’t unless you also buy an adapter.
AMD currently uses the AM4 socket, which is available on both newer and more feature-packed motherboards, plus older ones. If you’ve got an older AM4 motherboard, you should be able to get a BIOS update to make it compatible with the chips that we’ve reviewed. This can make AMD’s processors a better upgrade option, as you can swap out your old CPU for a new one and not change anything else.
However, note that the current generation of AMD chips will be the last to use the AM4 form factor, so if you have it in mind to upgrade the CPU in a couple of years then you should either go down the Intel route or wait for AMD’s next generation of processors.
With Intel’s chips, you have a choice of DDR4 and DDR5 RAM.
The motherboard you pick will determine your choice. Currently, there’s not a huge amount of difference in speed between the current generation of DDR5 and the top-end DDR4 RAM; in the future, much faster DDR5 RAM will be available. The main difference today is the price: DDR4 is much cheaper.
AMD chips all use DDR4 for now. It’s worth buying fast DDR4 RAM so that it’s not a bottleneck to your processor. A minimum of 16GB makes sense, but buy more if you’re a heavy user or like to have lots of applications open at the same time.
Intel CPUs also support PCI-E 5.0, which will mean even faster M.2 drives when they’re available. AMD chips only support PCI-E 4.0. That’s not a massive problem today, as the fastest SSDs are only PCI-E 4.0.
Final decision
Don’t buy more CPU than you need, as you’ll end up with an underutilised PC and you’ll have spent more than necessary. With that in mind, we’ve got some rule-of-thumb advice on getting the right chip for you. If you want a basic PC for web browsing, office work and the odd bit of photo editing, then an entry-level, quadcore or six-core processor will do the job. If you’re into media editing and like to play the occasional game at a resolution of 1080p or 1440p, then a mid-range six-core processor should suit you.
Once you start getting into more heavy video editing and you’re more demanding about your gaming, then an eight- to 12-core processor is more likely to suit your needs.
For those that really push their PCs with 3D modelling, CAD and high-end video editing, you’re looking at one of the higher-end models on this list.
Don’t buy more CPU than you need, as you’ll end up with an underutilised PC and you’ll have spent more than necessary