Drilling Down to the Cores
For many consumers who are on the hunt for a new desktop or laptop PC, one of the biggest considerations is the type of processor. Two of the CPUs most often in contention are the Intel Core i5 and Intel Core i7. Discounting Core i3 and m3 (mainly found in budget systems), Core i9 (powerful CPUs for gaming and performance PCs), and AMD processors (another story entirely), the difference between Intel Core i5 and Core i7 can seem daunting, especially when the prices seem so close together once they're in completed systems. We break down the differences for you.
Pricing and Marketing
Simply put, Core i5-equipped systems are less expensive than Core i7-equipped PCs. Intel has moved away from the star ratings it used with previous-generation Core processors in favor of a capability-driven marketing message. Essentially, the Core i7 processors have more capabilities than Core i5 CPUs. They will be better for multitasking, multimedia tasks, high-end gaming, and scientific work. Core i7 processors are certainly aimed at people who complain that their current system is "too slow." Spot-checking a system like the Dell XPS 13 Touch ultraportable, you'll find the Core i5 to be about $200 less expensive than a similarly equipped Core i7 system.
For the most part, you'll get faster CPU performance from Core i7 than Core i5. The majority of Core i7 desktop CPUs are quad-core processors, as are the majority of Core i5 desktop CPUs. However, there are mobile versions of both processors that are dual-core. You might also see the rare six- or eight-core Core i7, but that's usually found with the desktop-only, top-of-the-line Core X and Extreme Edition models. Simply put, the more cores you have in your CPU, the faster it will perform.
The Core nomenclature has been used for several generations of CPUs. Haswell, Broadwell, Sky Lake, and Kaby Lake CPUs use four-digit model names (such as the Intel Core i7-7700). Thankfully, unless you're shopping the used PC market, you'll only find Broadwell or older processors in closeout systems and budget PCs, while you'll find Sky Lake or Kaby Lake processors in most new PCs. Older-generation Nehalem, Westmere, Sandy Bridge and Ivy Bridge cores generally have lower performance. The essential takeaway is that to get better performance in each generation, buy a processor with a higher model number. For instance, an Intel Core i7-7600U generally has better performance than an Intel Core i5-7200U.
Give Me the Cache
In addition to generally faster base clock speeds, Core i7 processors have larger cache (on-board memory) to help the processor deal with repetitive tasks faster. If you're editing and calculating spreadsheets, your CPU shouldn't have to reload the framework where the numbers sit. This info will sit in the cache, so when you change a number, the calculations are almost instantaneous. Larger cache sizes help with multitasking as well, since background tasks will be ready for when you switch focus to another window. On currently available desktop processors, most i5 CPUs have 3MB to 6MB of L3 cache, while most i7 processors have 6 MB to 8MB.
A Word on Turbo Boost
Turbo Boost is an overclocking feature that Intel built into its processors. Essentially, it allows the processor to run faster than its base clock speed when only one or two processor cores are needed (like when you're running a single-threaded task that you want done now). Both Core i5 and Core i7 processors use Turbo Boost, with Core i7 processors achieving higher clock speeds.
Hyper-Threading
Intel Hyper-Threading uses multithreading technology to make the operating system and applications think that a processor has more cores than it actually does. Hyper-Threading technology is used to increase performance on multithreaded tasks. The simplest multithreaded situation is a user running several programs simultaneously, but there are other activities that take advantage of Hyper-Threading, like multimedia operations (such as transcoding and rendering) and Web surfing (loading different elements, like Flash content and images, simultaneously).
The quick explanation is that all Core i7 CPUs use Hyper-Threading, so an eight-core CPU can handle 16 streams, a four-core can handle eight streams, and a dual-core can handle four streams. Core i5 uses Hyper-Threading to make a dual-core CPU act like a four-core one, but if you have a Core i5 processor with four true cores, it won't have Hyper-Threading. For the time being, Core i5 tops out at handling four streams, using four real cores or two cores with Hyper-Threading.
Integrated Graphics
The Westmere generation of Core processors introduced Intel HD graphics, which are integrated graphics built into the CPU core itself. Previous Intel-integrated graphics were built onto the motherboard chipsets, rather than on the processor. You'll find Skylake sixth generation and Kaby Lake seventh generation processors have either Intel HD graphics (for example Intel HD Graphics 630), or Intel Iris/Iris Plus options. Note that while high-end Intel processors will let you play 3D games at medium quality settings, you will still need discrete GPUs from AMD or Nvidia to play 3D games at 1080p or 4K resolutions with ultra quality settings turned on.
The same numerical rules apply here, so Intel Iris Plus 650 performs better than Intel HD Graphics 630, which performs better than Intel HD Graphics 510. You'll find Iris Plus and higher-end Intel HD graphics on Core i7 CPUs, while Core i5 processors feature one of the myriad versions of Intel HD graphics, depending on the part number. Integrated graphics save power, since there's no extra graphics chip on your laptop or desktop's motherboard using power.
Core Outliers: X and Y
Intel recently announced a new Core X processor family aimed at high-performance users like extreme gamers and video editors. The Core i9-7980XE Extreme Edition processor, for example, has 18 cores and can process 36 threads simultaneously. It also retails for $1,999, and is overkill for most users. More reasonably priced X-Series processors include the Core i5-7640X ($242) with four cores, and the Core i7-7820X ($599) with eight cores. These CPUs are based on both Kaby Lake and Skylake architecture, depending on the model, and are designed to work with Intel's new LGA2066 socket and X299 motherboard chipset. You'll need a new PC, or at least a new motherboard, to play in this arena. Direct reviews of these chips are still pending, but they're being positioned as high-performance hardware for 3D CGI rendering, mathematical calculations on large data sets, 4K video processing, and of course gaming/game development.
One last complication involves the Kaby Lake versions of Intel's 4.5W mobile processors. Until recently, midrange and high-end versions of these power-saving CPUs were known as the Core m5 and Core m7, respectively. You'll find current and newer iterations under the Core i5/i7 Y-Series nomenclature, for example the Core i5-7Y54 and its higher-clocked sibling, the Core i7-7Y75. In our testing, these Y-Series processors are comparable to the higher-wattage (15W) Core i5 and i7 processors on everyday tasks, but are a bit slower performing in multimedia-creation apps like Handbrake and Photoshop.
Long story short: Intel Core i5 is made for mainstream users who care about performance, and Intel Core i7 is made for enthusiasts and high-end users. Only extreme users need to consider Intel's Core X-Series.