Intel i3,i5 or i7. What is the difference?

Intel has branded their new generation processors with very catchy names like i3, i5 and i7. Well looking at the names, we might think that these are processors having 3, 5 and 7 cores respectively. But this is a big myth. In reality i3 has two cores; i5 and i7 may have 2, 4 or 6 cores depending on the model. Then your next thought will be that if i3 is having two cores, how is it better than dual core processors? Also if i5 and i7 are having the similar number of cores, then why i7 is better than i5? I will try to address some these questions in this post.

The dual core processors can have two threads running over the two cores available, but in case of i3 processors we can have 4 threads running over the same two cores. This is made possible by incorporating a technology called Hyper-threading.

Hyper-threading works by duplicating certain sections of the processor (those that store the architectural state), but not duplicating the main execution resources. This allows a hyper-threading processor to appear as two "logical" processors to the host operating system, allowing the operating system to schedule two threads or processes simultaneously. When execution resources would not be used by the current task in a processor without hyper-threading, and especially when the processor is stalled, a hyper-threading equipped processor can use those execution resources to execute another scheduled task. Here is where the thread power of the Core i3 is superior to that of dual core which does not have this feature.

Another important feature introduced by Intel is the Turbo Boost Technology.

Quad core processors are very useful in speeding up the video rendering process but the advantage of having four cores is not fully exploited by the high end games we play.

Most of the high end games available today are not designed for quad cores; they use two cores at the max. Hence the other two cores remain idle and consume power even though they are not using it. Hence it would not be surprising to see a 3.2 GHz dual core processor perform better than a 2 GHz quad core processor which is effectively using just two cores to run the game. This is where the Turbo boost comes to the rescue of the quad cores.

When just one or two cores are being actively used; whatever power the other two or three cores would have consumed is redirected by turbo boost, over to the active cores, allowing them to run at higher speeds. Hence 2GHz quad core processor behaves like a dual core processor with a boosted speed of about 3.2 GHz.

Turbo Boost can increase the frequency of all four cores until they're running as fast as they can for the current workload. The Turbo Boost controller samples the current power consumption and chip temperature 200 times per second and makes whatever adjustments are necessary. 

Now that we have introduced the critical technologies which makes the Intel’s i series special, let’s focus on the difference between i3, i5 and i7.

The Intel core i3 is an entry level processor, which is meant for light users who use their desktops/laptops for simple day to day activities like browsing net, watching videos, playing songs, working on spreadsheets, word etc. These tasks do not require a very powerful CPU and hence technologies like turbo boost are not available for i3. Also they have a comparatively smaller cache size of 3 MB. But the bright side is that they are cheap and much more power efficient and less heat producing when compared to the previous Dual core/Core 2 duo line.

The Intel i5 is a mid-level processors which is meant for users who demand a little more speed and little resource intensive tasks like gaming, photo editing, multitasking, scientific computing etc. I5 supports Turbo boost technology but lack Hyper-threading feature that we see in i3 processors. It is faster and more energy efficient than the i3 processor. It also has a large cache size of about 6MB which further improves operational speed. But all these great features comes a greater price!

Finally the I7 processors are the High end processors for users who demand power and great speed. It is the top of the line processor and performs like a beast. It is suited for highly resource intensive tasks like video rendering, playing heavy duty games, video editing, software development, scientific computing etc. It has support for both Hyper-threading and turbo-boost which pretty much explains why it is Intel's finest processor. It has the largest cache size among three, which is typically about 8 MB. Also it is much faster and more power efficient compared to the other two. But with "Great Power comes greater responsibility" on your wallet.

Well I have tried my best to explain the difference between these processors. I hope this post will be helpful when you purchase your next laptop or desktop.