What's the difference between an Intel Core i3, i5 and i7

Generally speaking, Core i7s are better than

Core i5s, which better than Core i3s. Nope, Core i7 does not have seven cores nor

doesCore i3 have three cores. The numbers

areSimply indicative of their relative

processingpowers.

Processing powerProcessing power is the ability of a computer to manipulate data.Their relative levels of processing power are based on• Number of cores,• Clockspeed (in GHz)• Size of cache• Intel technologies like Turbo Boost and Hyper-Threading.

Number of cores• A core can be thought of as in individual

processor. • A dual-core processor, therefore has two

internal processors, a quad-core model has four.• All CPUs have one or more cores, with

each core being a processor itself.• Most commonly an Intel Core processor

will have two physical cores (dual-core) and also two virtual cores (which Intel calls Hyper-Threading).

Number of cores• More cores are useful for multi-tasking; for

example, you can run two applications at the same time, each one having access to its own dedicated processor.• If you buy a Core i7 Extreme Edition, you will

find up to 12 physical cores. Physical cores are better than virtual cores in performance terms.• The lowest number of cores can be found in

Core i3 CPUs, i.e., which have only two cores. Currently, all Core i3s are dual-core processors.

Number of cores• Currently all Core i5 processors,

except for the i5-661, are quad cores. The Core i5-661 is only a dual-core processor with a clockspeed of 3.33 GHz.

• Remember that all Core i3s are also dual cores. Furthermore, the i3-560 is also 3.33GHz, yet a lot cheaper. Sounds like it might be a better buy than the i5. What gives?• Even if the i5-661 normally runs

at the same clockspeed as Core i3-560, and even if they all have the same number of cores, the i5-661 benefits from a technology known as Turbo Boost.

Clockspeed• The CPU requires a fixed number

of clock ticks (or clock cycles) to execute each instruction.• The faster the clock, the more instructions

the CPU can execute per second.• Clock speeds are expressed in megahertz

(MHz) or gigahertz ((GHz).• One megahertz is equal to one million cycles

per scecond.• Generally more clockspeed results in more

heat generation and more power consumption.

Cache size• A processor's performance isn't determined by

clock speed alone, though. Other factors such as cache memory size also play a part.

• Cache memory, also called CPU memory, When a CPU finds it is using the same data over and over, it stores that data in its cache.

• Cache is even faster than RAM, because it's part of the processor itself.

• Here, bigger is better. Core i3 chips have 3- or 4MB, while i5s have 6MB and the Core i7s have 8MB.

• This is clearly one reason why an i7 outperforms an i5 — and why an i5 outperforms an i3.

Hyper-Threading• A thread in computing terms is a sequence

of programmed instructions that the CPU has to process.• If a CPU has one core, it can process only

one thread at once, so can only do one thing at once.• Hence, a dual-core CPU can process two

threads at once, a quad-core four threads at once. That's twice or four times the work in the same amount of time.• Hyper-Threading is a clever way to let a

single core handle multiple threads.

Hyper-Threading• A Core i3 with Hyper-Threading can

process two threads per core which means a total of four threads can run simultaneously.• The current Core i5 range doesn't have

Hyper-Threading so can also only process four cores.• i7 processors do have it, so can process

eight threads at once. Combine that with 8MB of cache and Turbo Boost Technology, and you can see why it's good to choose a Core i7 over an i5 or i3.

Intel Turbo Boost• The Intel Turbo Boost Technology allows a

processor to dynamically increase its clockspeed whenever the need arises.

• The maximum amount that Turbo Boost can raise clockspeed at any given time is dependent on the number of active cores, the estimated current consumption, the estimated power consumption, and the processor temperature.

• Core i3 processors don't have Turbo Boost, but i5 and i7s do.

• The Core i7-6700, for example, has a base clock of 3.4GHz, but can 'boost' up to 4GHz.