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April 20, 2017

Intel’s Core i7 is tempting, but you probably only need a Core i5

by John_A

Intel’s Core i5 and i7 processors are ubiquitous. Nearly every modern computer features one of these two chips, and unless you’ve specifically sought out a PC with an AMD processor, chances are you have a Core i5 or Core i7 purring away in your desktop or laptop. But what’s the difference between an i5 and an i7? Like most computer components, there are dozens of models at each tier to choose from, and it can get a little overwhelming.

This guide is designed to help you decide whether you need four cores or two, eight threads or four — and what those terms actually mean, in practice.

It’s worth noting, before we get started, that we’re talking specifically about Intel’s 7th-generation “Kaby Lake” chips and 6th-generation “Skylake” chips here. A lot of the information applies elsewhere, but the newer chips tend to provide noticeable feature and performance improvements over previous generations. You won’t save a lot of money buying CPUs older than the 6th or 7th-generations, and all but the most experienced builders will want to stay away from earlier Core i5 and Core i7 offerings.

What’s the difference?

Overall, Core i5 and Core i7 chips differ in the way they handle processing information. Core i5 processors are usually limited by the number of cores they have, for instance a quad-core i5 processor can maintain four “threads” at once — these “threads” are used by software to manage multiple tasks simultaneously, rather than queuing everything up for execution one-by-one.

Core i7 processors on the other hand, use a feature called “hyper-threading” to reach above and beyond the number of cores they have. So, a Core i7 processor with four cores can actually handle eight threads of data at once. Processors with hyper-threading can effectively double the number of threads they can handle at once.

For concurrent processing tasks — times when your PC needs to handle processor intensive tasks at the same time — a CPU with hyper-threading can make sure you experience minimal system slowdown. Without hyper-threading, a CPU might need to queue things up and process them one-by-one. This is all handled in the blink of an eye, but the cumulative effect can definitely be felt when you’re multi-tasking and running processor intensive applications.

Windows will actually detect extra threads as physical cores, and software will use them as such, but the performance gain is only a fraction of what an extra physical core will provide. Still, the extra threads are useful in demanding software.

Core i5 vs Core i7 on the desktop

Aside from the previously mentioned architectural differences between Core i5s and Core i7s, there are a few unique peculiarities you’ll find on the desktop versions of these processors.

Desktop Core i5s, for instance, almost always have four cores, and this means they’re more robust and powerful than their mobile counterparts. But even though Core i5 quads typically come pretty close to Core i7 clock speeds, they don’t feature hyper-threading and usually have smaller cache sizes — meaning they don’t perform as well on repetitive tasks.

Core i7 processors are a little different. Not only do they have larger cache sizes — meaning they’re better with repetitive tasks — but they typically have quicker clock speeds, and always feature hyper-threading. Another major difference is the number of cores available. On the desktop, Core i5s always have four cores, but Core i7s can have between four and ten cores. That means an eight core i7 can handle 16 threads at once with hyper-threading, and a ten-core i7 processor can handle 20 threads at once.

Core i5 vs Core i7 on laptops

Mobile processors are a slightly different story. Where desktop Core i5s never feature hyper-threading, some mobile versions do, allowing mobile dual-core i5 processors to handle four threads at once.

The Core i5 processors found in laptops come in two configurations: Dual-core with hyper-threading, and quad-core without. The difference between these two types of mobile Core i5s usually comes down to clock speed — quads are generally a little quicker.

Similarly, mobile Core i7s are found in two flavors, dual-core and quad-core, but both feature hyper-threading.

So what’s the difference between a mobile dual-core i7 and a mobile dual-core i5 if they both feature hyper-threading? Well, mobile Core i7s feature larger cache sizes, and they’re usually a little quicker when it comes to clock speed.

Quad-cores sometimes have lower clock speeds than dual-core chips. This is most common in mobile chips that must squeeze into a tight power envelope. What does this mean? A dual-core with a high clock speed will beat a quad-core with a low clock speed in applications that don’t use many cores; however, the quad-core will be quicker in applications that do. If the quad has more cores and a higher clock, it will always be quicker.

Should you buy a Core i5 or a Core i7?

So, which processor should you invest in? That depends on your needs, but for most people a Core i5 is going to be the most sensible choice.

While there are a lot of factors in determining overall system performance, most of the time, a Core i5 processor won’t end up bottlenecking your day-to-day performance. Most people, including gamers, will find a Core i5 quad-core perfectly adequate.

A Core i7 makes sense only for users who don’t mind paying a premium for more power, or users who often run extremely demanding software. For example, shaving a few seconds off every minute of encoding 1080p video adds up, if you regularly encode projects that are a couple hours long.

While nice to have, the performance impact of hyper-threading is very dependent on software. Only applications specifically designed to take advantage of multiple threads will see a performance increase. The feature is most useful to people who run productivity applications.

Intel Core i5 on Amazon Intel Core i7 on Amazon

Updated 4-18-2017 to include information about the latest i5 and i7 processors.

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