Intel Core i3, Core i5, and Core i7 CPUs have been around for a few years now, but some buyers still get stumped whenever they attempt to build their own systems and are forced to choose among the three. With the more recent 7th Generation (Kaby Lake) architecture now available in notebooks that are on store shelves, and the rest of the processors expected to launch in January, we expect the latest wave of buyers to ask the same kind of questions.
Core i3, Core i5, Core i7 — the difference in a nutshell
Generally speaking, Core i7s are better than Core i5s, which are in turn better than Core i3s. Core i7 does not have seven cores nor does Core i3 have three cores. The numbers are simply indicative of their relative processing powers.
Their relative levels of processing power are based on a collection of criteria involving their number of cores, clock speed (in GHz), size of cache, as well as technologies like Turbo Boost 2.0 and Hyper-Threading.
Note: Core processors can be grouped in terms of their target devices, i.e., those for laptops and those for desktops. Each has its own specific characteristics/specs.
Intel recently launched its 7th Generation processors to power fanless 2-in-1 (convertible laptop/tablet) devices and ultrathin notebooks – known as the Y-series and U-series processors. Theses processors are designed to strike a balance between performance and mobility, including longer battery life.
The second phase of 7th generation processors, including those for desktops, gaming notebooks, workstations and more, will launch in January. We’ll update this article to cover these processors when that time comes.
Number of cores
The more cores there are, the more tasks (known as threads) can be served at the same time. Since the 7th Generation Y-series and U-series are designed for maximum battery life and fanless designs, all processors in these families feature two cores.
Desktop processors, starting from the 6th generation Core i5 and i7 desktop processors are quad core and hence can handle more tasks at the same time, while lower end Core i3 desktop processors are dual core.
At this point, I’d like to grab the opportunity to illustrate how a number of factors affect the overall processing power of a CPU beyond just number of cores, and determine whether you should consider i3, an i5, or an i7.
Even if a CPU only has two cores (known as dual core), most Intel CPUs benefit from a technology known as Intel Turbo Boost 2.0.
Intel Turbo Boost Technology 2.0
The Intel Turbo Boost Technology 2.0 allows a processor to dynamically increase its clock speed whenever the need arises. The maximum amount that Turbo Boost can raise clock speed at any given time is dependent on the number of active cores, the estimated current consumption, the estimated power consumption, and the processor temperature.
Intel Turbo Boost Technology 2.0 is available on the 7th Generation Core i7 and Core i5 processors currently available in notebooks.
Whenever the CPU finds that it keeps on using the same data over and over, it stores that data in its cache. Cache is just like RAM, only faster — because it’s built into the CPU itself. Both RAM and cache serve as holding areas for frequently used data. Without them, the CPU would have to keep on reading from the hard disk drive, which would take a lot more time.
Basically, RAM minimises interaction with the hard disk, while cache minimises interaction with the RAM. Obviously, with a larger cache, more data can be accessed quickly. Intel’s latest processors feature Intel Smart Cache, which dynamically allocates shared cache to each processor core, based on workload, reducing latency and improving performance.
The 7th Generation Core i3 and Core i5 processors in the U-series and Y-series have either 3MB or 4MB of cache. The Core i7s in the range have 4MB of cache. This is clearly one of the reasons why an i7 outperforms an i5.
Intel Hyper-Threading Technology
Strictly speaking, only one thread can be served by one core at a time. So if a CPU is a dual core, then supposedly only two threads can be served simultaneously. However, Intel has a technology called Hyper-Threading. This enables a single core to serve multiple threads.
The U and Y series 7th Gen processors available in notebooks today are all dual core. However, thanks to Hyper-Threading Technology they can serve two threads per core. In other words, a total of four threads can run simultaneously. This means highly threaded applications can get more work done in parallel, completing tasks sooner.
The upshot is that if you do a lot of things at the same time on your PC, then it might be worth forking out a bit more for a Core i7. However, if you use your PC to check emails, do some banking, read the news, and download a bit of music, you might be equally served by the cheaper Core i3.
Another factor in this deliberation is that more and more programs are being released with multi-thread capability. That is, they can use more than one CPU thread to execute a single command. So things happen more quickly. Some photo editors and video editing programs are multi-threaded, for example.
Hopefully this gives you some insight for your next CPU selection.