Intel Core i3 vs. i5 vs. i7 – Which One Do You Really Need

The processor is the brain of a computer — but understanding the difference between processors requires a lot of brainpower of your own!

Intel hasn’t made it any easier for customers with their strange naming schemes, and the question we get asked most often is: What’s the difference between an i3, i5, or i7 processor? Which one should I buy?

It’s time to demystify that. In this article, we won’t be touching on Intel’s other processors like the Pentium series or the new laptop-centric Core M series. They’re good in their own right, but the Core series is the most popular and confusing, so let’s just focus on that.

Understanding the Model Numbers
Purely speaking, it’s very simple. An Intel Core i7 is better than a Core i5, which in turn is better than a Core i3. The trouble is knowing what to expect within each tier. Things go a little deeper.

First, i7 does not mean a seven-core processor! These are just names to indicate relative performance.

Typically, the Core i3 series has only dual-core processors, while the Core i5 and Core i7 series have both dual-core and quad-core processors. Quad-cores are usually better than dual-cores, but don’t worry about that just yet.

Intel releases “families” of chipsets, like the new 6th generation Skylake family or the older 5th generation Haswell family. Each family, in turn, has its own line of Core i3, Core i5, and Core i7 series of processors.

You can spot which generation a processor belongs to by the first digit in its four-digit model name. For example, the Intel Core i3-5200 belongs to the 5th generation. Remember, Intel’s new generations won’t support Windows 7, but since Windows 10 is a free upgrade anyway, go for the latest generation possible.

Pro Tip: Here’s a useful rule of thumb. The other three digits are Intel’s assessment of how the processor compares to others in its own line. For example, an Intel Core i3-5350 is superior to the Core i3-5200 because 350 is higher than 200.

End Letters: U vs. Q. vs. H vs. K
Things have changed since we last looked at Intel’s processor list. The model number will typically be followed by one or a combination of the following letters: U, Y, T, Q, H, and K. Here’s what they mean:

U: Ultra Low Power. The U rating is only for laptop processors. These draw less power and are better for the battery.
Y: Low Power. Typically found on older generation laptop and mobile processors.
T: Power Optimized for desktop processors.
Q: Quad-Core. The Q rating is only for processors with four physical cores.
H: High-Performance Graphics. The chipset has one of Intel’s better graphics units in it.
K: Unlocked. This means you can overclock the processor above its rating.

Understanding these letters and the numbering system above will help you know what a processor offers just by looking at the model number, without needing to read the actual specifications. Of course, before making a buying decision, it’s advisable to check the details at ark.intel.com.

You can find the meaning of other suffixes at Intel’s guidelines on processor numbers.

Hyper-Threading: i7 > i3 > i5
As you can see above, Intel specifically writes U and Q for the number of physical cores. Well, what other kinds of cores are there, you ask? The answer is virtual cores, activated through a technology called Hyper-Threading.

In layman’s terms, hyper-threading allows a single physical core to act as two virtual cores, thus performing multiple tasks simultaneously without activating the second physical core (which would require more power from the system).

If both processors are active and using hyper-threading, those four virtual cores will compute faster. However, do note that physical cores are faster than virtual cores. A quad-core CPU will perform much better than a dual-core CPU with hyper-threading!

The Intel Core i3 series has hyper-threading. The Intel Core i7 series supports hyper-threading, too. The Intel Core i5 series does not support it.

Turbo Boost: i7 > i5 > i3
On the other hand, the Intel Core i3 series does not support Turbo Boost. The Core i5 series uses Turbo Boost to speed up your tasks, as does the Core i7 series.

Turbo Boost is Intel’s proprietary technology to intelligently increase a processor’s clock speed if the application demands it. For example, if you are playing a game and your system requires some extra horsepower, Turbo Boost will kick in to compensate.

Turbo Boost is useful for those who run resource-intensive software like video editors or video games, but it doesn’t have much of an effect if you’re just going to be browsing the web and using Microsoft Office.

Cache Size: i7 > i5 > i3
Apart from Hyper-Threading and Turbo Boost, the one other major difference in the Core line-up is Cache Size. Cache is the processor’s own memory and acts like its private RAM — and it’s one of the little-known specs that slows down your PC.

Just like with RAM, more cache size is better. So if the processor is performing one task over and over, it will keep that task in its cache. If a processor can store more tasks in its private memory, it can do them faster if they come up again.

The Core i3 series typically has up to 3 MB of cache. The Core i5 series has between 3 MB and 6 MB of cache. The Core i7 series has between 4 MB and 8 MB of cache.

Graphics: HD, Iris, Iris Pro
Ever since graphics were integrated on the processor chip, it’s become an important decision point in buying CPUs. But like with everything else, Intel has made the system a little confusing.

There are now typically three levels of graphics units: Intel HD, Intel Iris, and Intel Iris Pro. You’ll see a model name like Intel HD 520 or Intel Iris Pro 580… and that’s where the confusion begins.

Here’s a brief example of how mind-boggling it can be. Intel HD 520 is a basic graphics chipset. Intel Iris 550 is better than Intel HD 520, but also basic. But Intel HD 530 is a high-performance graphics unit and is better than Intel Iris 550. However, Intel Iris Pro 580 is also a high-performance graphics unit and better than Intel HD 530.

The best advice for how to interpret these? Just don’t. Instead, rely on Intel’s naming system. If the processor’s model ends with an H, you know it’s a high-performance unit.

Comparing Cores i3, i5, i7

Generally speaking, here’s who each processor type is best for:

Core i3: Basic users. Economic choice. Good for browsing the web, using Microsoft office, making video calls, and social networking. Not for gamers or professionals.
Core i5: Intermediate users. Those who want balance between performance and price. Good for gaming if you buy an HQ processor or a Q processor with a dedicated graphics processor.
Core i7: Professionals. This is the best Intel can do right now.
How Did You Choose?
This article provides a basic guide for anyone looking to buy a new Intel processor but is confused between Core i3, i5, and i7. But even after understanding all this, when it’s time to make a decision, you might need to choose between two processors from different generations because they’re priced the same.

When you’re comparing, my best tip is to head to CPU Boss where you can compare both processors and get a detailed analysis, as well as ratings. If you don’t understand the jargon, just go with the rating and the basic advice. If you understand jargon, CPU Boss has all the details you’ll need.