Best Intel processor: Core i3, i5, i7 and i9 explained

Picking a processor is one of the tougher choices you’ll make when buying a new desktop PC or laptop. Intel makes most of the CPUs on the market, but which is the best Intel processor for you?

However, the chip-maker makes a lot of CPUs. There are various models – not just for desktops and laptops, but different styles within these categories too. Here, we’ll break down the differences between Core i3 and Core i9, and look at what the jumble of numbers and letters in an Intel CPU name actually mean.

And with Intel’s new 9th Gen CPUs recently released, it’s even tougher to find your ideal processor. The Intel Core i9-9900K, for example, might be an absolute powerhouse for creative tasks, but it’s not necessarily the best Intel processor to buy for gamers. Yup, it’s very much a head-scratcher.

To prevent your brain from overheating, we’ve created this guide to help you find the very best Intel processor to satisfy your needs.

Related: Intel Core i9-9900K review

Best Intel processor

Best Intel processor: Breaking down the Intel code

Unless you want to shop for a refurbished or end-of-line bargain, first make sure you look at a 8th or 9th Gen CPU model.

You can tell if a CPU belongs in this family by looking at the number directly after the ‘i3’, ‘i5’, ‘i7’ or ‘i9’ in the processor name. An Intel Core i9-9900K is a 9th-generation CPU. An i7-8550U is an 8th-generation chipset and the i7-7500U is from the 7th.

While the 9th generation processors currently offer the best Intel Core processors, we’d currently suggest opting for an 8th-gen model instead given their more affordable prices. Buy any CPU older than that, however, and you’ll see a substantial dip in performance.

Best Intel processor

The letter at the end of a CPU’s name is the second most important part of the Intel code to note. In desktop CPUs, you’ll see either no letter at all, or a ‘K’.

Need to stick to a tight budget, or making a PC for basic tasks? You’ll be fine with an Intel CPU without a letter. These are standard consumer-grade processors.

K-series CPUs are ‘unlocked’. This means you can overclock them more freely, increasing how hard they work to improve performance.

These processors are for enthusiasts who put extra thought into the cooling system in their PC. Overclocking increases the level of heat a CPU creates, and can cause issues with a stock cooler. You can buy ‘standard’ and ‘unlocked’ versions of the Core i3, i5 and i7 processors.

Dig a little deeper and you’ll find CPUs with ‘X’, ‘T’ and ‘B’ letters too. T and B CPUs have extra features for business use. And X-series processors are part of the 7th generation. They remain the fastest processors around, but are far too expensive for most budgets.

The 18-core Intel i9-7980XE costs £1800, for example. You can make a very high-end computer for this price.

Related: Best desktop PCs

Best Intel processor

Best Intel processor: Laptop CPUs explained

The lineup of Intel laptop processors is fairly simple these days. If you’re after a system you can carry around and will last a good while off a charge, you’ll want a processor that ends in a ‘U’. These are ultra-low voltage processors made for high power efficiency.

‘H’-series processors are used in the highest-performance laptops, such as the Alienware 15. They consume more power and will therefore offer shorter battery life, but performance will be better.

Right at the top of the laptop lineup sits an ‘HK’ CPU, the i9-8950HK. Just like K-series desktop processors, this one is unlocked to allow for greater overclocking.

In one of the most exciting updates in Intel laptop CPUs for some time, there are now also ‘G’ processors. These incorporate Radeon RX Vega M graphics processors that often deliver PlayStation 4-beating gaming performance in a portable laptop.

If you want a desktop and you don’t plan to overclock it, buy a standard Intel CPU without a letter on the end of its name. Long-lasting laptops use U-series processors. And if you want a gaming PC that isn’t big or heavy, look for a model such as the HP Spectre X360 with a G-series chipset.

The recent announcement of the Whiskey Lake and Amber Lake-based CPUs bring some new changes to the table, namely support for gigabit Wi-Fi, faster video rendering, integrated LTE and a number of efficiency gains which all add up to better power management and improved performance over all. That said, all of the Whiskey Lake CPUs announced so far bear the U-series suffix, while the Amber Lake CPUs are all Y-series models.

Related: Best laptops

Best Intel processor

Best Intel processor: Core i3 vs i5 vs i7 vs i9 in a desktop

Now that we’ve explained some of the more confusing bits of Intel’s naming conventions, let’s look at which model you should opt for: Core i3, i5, i7 or i9?

As you’d expect, performance increases as you upgrade through the ranks from a Core i3 to a Core i9. But we need to break it down further.

Intel Core i3 desktop processors have four cores. They offer excellent performance for their cost, but they lack support for two core technologies found in higher-end CPUs. These are Hyper-Threading and Turbo Boost.

Hyper-Threading creates virtual cores to operate in a way that a processor with more cores would operate. Turbo Boost dramatically increases the clock speed when more power is needed.

Intel Core i5 desktop CPUs have six cores. Like Core i3 models, they don’t offer Hyper-Threading, but they do have Turbo Boost.

Core i7 processors have both Turbo Boost and Hyper-Threading. They may have six cores like an Intel Core i5, but can operate as if they have 12 cores.

Intel Core i9 CPUs, meanwhile, offer eight cores. The i9 is the most powerful option of the Intel Core ranges, so would be the processor to plump for if you’re not shy spending money.

Related: Best graphics cards

So, which do you need – Turbo Boost or Hyper-Threading? Turbo Boost is useful for most people as it increases the maximum performance of a processor.

Hyper-Threading would prove most useful for heavy multi-taskers and those who use applications such as video editor Adobe Premiere Pro or 3D rendering software. It’s less useful for games or simple applications, which don’t exploit a huge number of cores.

However, this doesn’t mean there’s no benefit to be had from a higher-end CPU if you don’t use such demanding software. Higher-end processors also have higher clock speeds, meaning each of the cores is more powerful, and has a larger CPU cache. This is used to store data handled by the CPU. The larger the cache, the smoother it will operate.

A Core i3 CPU has 6MB, a Core i5 9MB and a Core i7 has 12MB. This a reminder that there’s more to a CPU’s performance than just clock speed, and the number of cores it features.

Here’s a run-down of the main models to consider:

Intel Core i3-8100

Don’t turn your nose up at the Core i3 too quickly. It’s a fantastic sub-£100 brain for an everyday PC or low-cost gaming setup. You can use a relatively high-end graphics card, such as an Nvidia GTX 1070 with this CPU, without much bottlenecking.

Intel Core i5-8400

This is the best Intel processor to buy for the majority of people. It’s a powerful 4-core CPU offering great general performance, and it has enough power to pair with the most expensive consumer graphics cards around. For around £10 more, you can upgrade to the i5-8500, which has a slightly higher clock speed. But the performance difference is minor.

Intel Core i5-8600K

If you want to be able to overclock your CPU significantly, but don’t want to spend thousands on a setup, check out the Intel Core i5-8600K. The price is reasonable, and it’s roughly 15% more powerful than the i5-5400 – even before you start overclocking.

Intel Core i7-8700K

Let’s get serious. The Intel Core i7-8700K has six cores with 12 threads, a 4.7GHz turbo mode and 3.7GHz standard clock speed. While single-core speeds are only a tiny bit better than those of the i5-8500K, its two additional cores result in a more than 40% boost to multi-core performance.

Best Intel processor: 9th Gen Intel Core CPUs

There’s a new generation of Intel Core CPUs on the market, giving you even more options. Note though, that we’ve only been able to test the Intel Core i9-9900K so far, so we can’t comment on which is the best processor for you just yet.

Intel Core i9-9900K

Look at the spec sheet, and the i9-9900K seems to be a powerful beast – eight cores and 16 threads are not to be messed with. Benchmark tests testify that this is one of the very best consumer processors for creative tasks. But if you’re priority is gaming, you’ll find better value with the Intel Core i7-8700K.

Intel Core i7-9700K


Potentially being the perfect middle-ground of the 9th Gen Intel Core processors, the i7 boasts eight cores and eight threads at a more affordable price than the i9. Again, we’re yet to put this CPU through our testing, so we’re currently unable to comment on performance.

Intel Core i5-9600K


Six cores and six threads seems rather measly compared to the 9th Gen i9, but Intel promises that it still offers a competitive performance. We haven’t actually been able to review the Intel Core i5-9600K yet, but we’ll make sure to update this section as soon as we get our hands on it.

Related: Best laptops

Best Intel processor: Core i3 vs i5 vs i7 vs i9 in a laptop

The situation in laptops is a little different. First, relatively few laptops use Core i3 processors compared to Core i5 and i7, though it’s worth noting that two of the six Whiskey Lake and Amber Lake CPUs announced at IFA 2018 are Core i3’s.

Secondly, unlike the desktop version of the Core i3’s, which are all quad-core CPUs, laptop Core i3’s are dual-core processors which feature both Hyper-Threading and Turbo Boost. Where are all the Core i3 laptops? This ‘entry-level’ processor hasn’t been around for as long as its Core i5 and i7 siblings, and often isn’t deemed low-end enough to fit into truly affordable laptops.

Manufacturers often use AMD and Intel Pentium CPUs in their low-cost models instead. The Intel Core i5-8250U and i7-8550U are very popular, however.

The Core i5 model has four cores, eight threads and Turbo Boost. So does the Core i7, but its clock speed and turbo are both faster. There isn’t a radical difference in the performance of these models, however.

There’s a greater difference when you switch to an H-series chipset. These are more power-hungry processors, the kind found in high-performance laptops that might only last a couple of hours off a charge.

The Core i5-8300H has four cores, eight threads – similar to the i5-8250U model made for slimmer laptops. However, the Core i7-8750H has six cores and 12 threads, giving it dramatically higher multi-core power.

Right at the top of the tree, the Core i9-8950HK has six cores and 12 threads, too, but is around 20% more powerful than the Core i7. And it’s more overclockable. It’s an enthusiast CPU.

Here are the top CPUs you should look out for:

Intel Core i5-8250U
Found in laptops £550+

This is the best Intel processor to seek out if you want a portable laptop with excellent performance. Lots of premium and mid-range laptops use it, and it’s almost twice as powerful as the comparable model from the previous generation. Video editing? 3D modelling? The 8th-gen Core i5 is powerful enough to handle these advanced apps.

Intel Core i7-8550U
Found in laptops £650+

Most ultra-premium slim and light laptops use this processor. It isn’t dramatically more powerful than the Core i5 version, but you do get a little more pep, with slightly higher clock speeds and a larger cache. CPU upgrades in laptops often come as part of a RAM and SSD bundle too, for a more compelling overall package. The highest-end 13-inch version of Apple’s MacBook Pro is powered by an i7-8559U CPU.

Intel Core i7-8750H
Found in laptops £850+

A true performance laptop will have one of these H-series CPUs. It has an extra two cores over its U-series alternative, for much higher multi-core performance. However, its TDP – the amount of heat it creates – is much greater too, so you’re unlikely to find this CPU in slim and light laptops.

Intel Core i9-8950HK
Found in laptops £2000+

Oddly enough, the move from Core i7 to i9 isn’t actually as great a leap as the one between the U-series and H-series processors. It’s 5-15% faster than the i7. However, it also allows for greater overclocking.

Intel Core i7-8705G
Found in laptops £1899+

This is perhaps the most ‘fun’ CPU Intel has made to date. It incorporates Radeon RX Vega M GL graphics, radically better than the GPU of any other Core-series CPU. More powerful than an Nvidia GTX 1050 GPU, there’s enough power here to provide a true ‘gaming’ laptop experience.

Related: Best MacBook

Best Intel processor: Real-world performance and gaming

If you do a lot of video editing or 3D rendering, then the greater the CPU power, the better. However, there are more important considerations if you want a productivity PC or a system for games.

An Intel Core i3 has enough power to run Windows 10 well, but you need an SSD rather than a hard drive for slick performance.

The G-series laptop CPUs are also the only models with good gaming abilities baked in. An Intel Core i5-8305G will let you play The Witcher 3 at High graphics settings, 1080p resolution, at around 50fps.

All other Intel CPUs use a version of the UHD 630 graphics chipset. It will play The Witcher 3 at Low graphics settings, 720p, at around 23fps – which isn’t great.

No Intel desktop CPU is any good for gaming on its own. And if you want to find the right processor to put at the heart of a gaming rig, we’d recommend spending more on the GPU and less on the CPU if the budget is tight.

For example, a Core i3-8100 CPU with an Nvidia GTX1080 will provide better frame rates than a Core i7-8700 CPU with Nvidia GTX1060 GPU. That said, we do recommend treating the Core i5-8400 as an absolute minimum, if you want a CPU to be paired with a very high-end GPU.

With certain games, a lower-end CPU will act as a bottleneck. This is particularly true of games such as Civilization 6 and Total War: Warhammer 2, as a result of all the background calculations involved. Most glossy action adventure games are a lot more GPU-led, and will run fine with a Core i3.

Related: Best PC games

Best Intel processor: Want to get a little deeper?

Primer: what is clock speed? The GHz figure represents the number of clock cycles (calculations) a processor can manage in a second. Put simply, a bigger number means a faster processor.

For example, 3.6GHz means 3,600,000,000 clock cycles. This figure shouldn’t be used to compare processors from different families, generations or manufacturers, however. Bigger isn’t better when comparing AMD and Intel, or 2nd-gen to 9th-gen Intel processors. Different processor families have different levels of efficiency, so how much they get done with each clock cycle is more important than the GHz number itself.

Turbo Boost dynamically increases the clock speed of Core i5 and i7 processors when more power is required. This means the chip can draw less power, produce less heat (most of the time) and only boost when it needs to.

Turbo Boost means you can’t just look at standard clock speed. For example, although a Core i3-8100 runs at 3.6GHz compared with 1.6GHz for the Core i5-7600, the i5 chip can boost up to 3.6GHz when required, so will end up being quicker since it also has more cores.

The more a processor boosts its clock speed, the more heat it will produce. As such, the processors can only Turbo Boost for a limited time, while they remain within a certain temperature range. During long periods of heavy processor activity using all a processor’s cores – such as video encoding – a chip may not Turbo Boost much at all, since it might be too hot to do so safely.

Turbo Boost is a significant part of the reason Core i5 and Core i7 processors outperform Core i3 models in single-core-optimised tasks, even though they have lower base clock speeds.