Laptop CPUs 1 Not all Core i5 chips are alike
Bewildered by the range of CPUs on offer? Here are the key facts you need to know before choosing your laptop
When choosing a laptop, the processor is always a big concern. It’s commonly assumed that, above all else, the CPU determines whether or not a laptop will suit your needs, and if you buy the wrong model you’re doomed to a frustrating and laggy experience.
Indeed, Intel has encouraged that idea by dividing its processors up into the Core i3, i5 and i7 families (plus a small number of high-flying i9 chips). The mere existence of an i7 option inevitably inspires doubts about whether you can get by with a Core i5.
Yet, in reality, the branding doesn’t tell you much about performance. For a simple proof of that, check out our graphs on p90: you’ll see Core i7 systems merely matching Core i5 laptops in real-world performance, or even lagging behind them. So here are the key things you need to know about laptop processors.
You might think that all Core i5 chips would deliver roughly equivalent performance (and likewise for Core i3 and i7 models). Nothing could be further from the truth. For one thing, the Core i5 chips found in laptops will never be as powerful as desktop versions as they’re designed to target a different balance of performance and energy-efficiency.
What’s more, the range divides not only into various models with different clock speeds, but also across multiple series with different performance characteristics. Case in point: most laptops this month use U-series processors, while the PC Specialist Cosmos employs a more powerful H-series model. This gives it a big boost in performance at the expense of power consumption. The key takeaway is: focus on real-world performance, not branding.
2 Speed is only half of the story
A processor with a maximum frequency of 4.6GHz will surely be faster than one that only goes up to 3.4GHz, right? Well, sometimes. The catch is that when a processor is running at its top speed it gets very hot and, before long, the system may have to reduce its operating frequency to avoid overheating. A fast clock speed will always help with short, sharp operations such as our imageediting benchmark, but for more substantial workloads the overall performance advantage is often smaller than you’d imagine. That’s worth bearing in mind before you splash out on a nominally faster chip.
3 There’s not much difference between Core i5 and Core i7
There’s no hard and fast rule about what defines a Core i5 chip as opposed to a Core i7. In the past, multitasking capabilities have been the key differentiator, but all the i5 and i7 chips in this Labs have four cores, with Hyper-Threading allowing each core to process two threads at once.
They also all use the same integrated GPU, and are built on the same 14nm process with a nominal power draw of 15W. The main difference is the amount of on-chip cache: Core i5 models have 6MB, while the i7 features 8MB, allowing it to process more data and instructions at full speed without having to interface with slower system RAM. Aside from this, Core i7 models also tend to support higher clock speeds – but, as we note above, the benefit of that isn’t always as big as it appears.
In case you’re wondering, current Core i3 chips have only two physical cores and a lesser 4MB of on-chip cache. Older models have lacked Turbo Boost or Hyper-Threading, but both are included in the current range – so while an i3 is less powerful than a Core i5, it’s still fine for everyday desktop tasks.
4 Generations are less significant than they used to be
The first digit of a chip’s model number tells you which “generation” of the Core platform it’s from. Almost all of the CPUs in this month’s Labs are from the eighth or ninth generation, introduced in 2017 and 2018 respectively, and this tells you certain things about their design and manufacture. Truthfully, though, there’s no need to get bogged down in the minutiae of Intel’s internal processes: compare each laptop’s performance and features directly, and make your decision based on the things that matter.
If you’re not in a hurry, you could alternatively wait for the company’s forthcoming tenth-generation processors, which will include built-in support for 802.11ax (also known as Wi-Fi 6) and enhanced graphical performance. On past form these should arrive before the end of the year – but that hasn’t been officially confirmed yet.