There are three main difference between core i3, core i5 and core i7
1. Intel
Turbo Boost
The Intel Turbo Boost
Technology 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.
For the
Core i5-4570T, its maximum allowable processor frequency is 3.6GHz. Because
none of the Core i3 CPUs have Turbo Boost, the i5-4570T can outrun them
whenever it needs to. Because all Core i5 processors are equipped with the
latest version of this technology — Turbo Boost 2.0 — all of them can outrun
any Core i3.
2. Cache
size
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. The Haswell
(fourth generation) Core i3 processors have either 3MB or 4MB of cache. The
Haswell Core i5s have either 4MB or 6MB of cache. Finally, all Core i7 CPUs
have 8MB of cache, except for i7-4770R, which has 6MB. This is clearly one
reason why an i7 outperforms an i5 — and why an i5 outperforms an i3.
3. 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.
At DCA Computers,
we regularly hear across the sales counter, “I don’t mind paying for a computer
that will last, which CPU should I buy?” The sales tech invariably responds
“Well that depends on what you use your computer for.” If it’s the scenario
described above, we pretty much tell our customers to save their money and buy
an i3 or AMD dual core.
Another
factor in this deliberation is that more and more programs are being released
with multithread 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.
