Core Vs Clock

What Is a Core?

Each CPU “core” is actually a separate central processing unit, which is the part of the CPU that actually does the work. For example, a dual-core chip may look like a single CPU chip, but it actually has two physical central processing units on the chip.

Additional central processing units allow a computer to do multiple things at once. If you’ve ever used a single-core CPU and made the upgrade to a dual-core CPU, you should have noticed a significant difference in how responsive your computer is.

For example, let’s say you’re extracting an archive file and browsing the web at the same time. If you had a single-core CPU in your computer, web browsing wouldn’t be very responsive. The single core would have to split its time between web browsing and file-extraction tasks. If you had a dual-core CPU with two cores, one core would work on extracting the file while the other core did your web-browsing work. Web browsing would be much faster and more responsive.

Whether you’re doing multiple things at once or not, your computer is often doing system tasks in the background and you can benefit from additional cores to keep the operating system responsive. Applications can also be written to take advantage of multiple cores. For example, Google Chrome renders each website with a separate process. This allows Google Chrome to use different CPUs for different websites rather than using a single CPU for all browser-related tasks.

Clock speed

Also called clock rate, the speed at which a microprocessorexecutes instructions. Every computer contains an internal clock that regulates the rate at which instructions are executed and synchronizes all the various computer components. 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).

The internal architecture of a CPU has as much to do with a CPU's performance as the clock speed, so two CPUs with the same clock speed will not necessarily perform equally. Whereas an Intel 80286 microprocessor requires 20 cycles to multiply two numbers, an Intel 80486 or later processor can perform the same calculation in a single clock tick. (Note that clock tick here refers to the system's clock, which runs at 66 MHz for all PCs.) These newer processors, therefore, would be 20 times faster than the older processors even if their clock speeds were the same. In addition, some microprocessors are superscalar, which means that they can execute more than one instruction per clock cycle.

Clock Speed vs. Cores

CPUs have a clock speed – think of it as how fast the CPU does work. (That’s actually an imperfect analogy as the truth is a lot more complicated, but it will have to do for now.)

For example, Intel’s Core i5-3330 processor has a clock speed of 3 GHz and is a quad-core processor, which means it has four cores. All four cores in this Intel i5 processor are each running at 3 GHz.

Dual Core, Quad Core & More

Phrases like “dual core,” “quad core,” and “octo core” all just refer to the number of cores a CPU has:

• Dual Core: Two cores.
• Quad Core: Four cores.
• Hexa Core: Six cores.
• Octo Core: Eight cores.
• Deca Core: Ten cores.

Hyper-Threading

Intel CPUs use a technology referred to as “hyper-threading technology.” With hyper-threading, each physical core presents itself to the system as two logical cores. In the screenshot above, we’re not using an octo-core CPU – we’re using a quad-core CPU with hyper-threading.

This improves performance to some degree, but a quad-core CPU with hyper-threading is nowhere near as good as an octo-core CPU. You still only have four physical cores, although some tricks allow them to do a bit more work at once.

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