Hyper-Threading

Hyper-Threading
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.

For instance, a Core i3, which is only a dual core, can actually serve two threads per core. In other words, a total of four threads can run simultaneously. Thus, even if Core i5 processors are quad cores, since they don’t support Hyper-Threading (again, except the i5-4570T) the number of threads they can serve at the same time is just about equal to those of their Core i3 counterparts.

This is one of the many reasons why Core i7 processors are the creme de la creme. Not only are they quad cores, they also support Hyper-Threading. Thus, a total of eight threads can run on them at the same time. Combine that with 8MB of cache and Intel Turbo Boost Technology, which all of them have, and you’ll see what sets the Core i7 apart from its siblings.

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 an i5 or 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 i3.

Imp links:
https://www.pugetsystems.com/labs/articles/Specs-Explained-CPU-137/#TurboBoost
https://www.pugetsystems.com/labs/articles/Haswell-Core-i3-vs-i5-vs-i7---Which-is-right-for-you-475/