How Many CPUs Do You Have?

CPUs

Most people regard the central processing unit (CPU) as the square-shaped microprocessor that fits into a single socket on a motherboard. However, some chips contain two or four or even more CPUs. Each of these may contain separate processors.

To answer the question in the title, we will start by pressing Ctrl + Shift + Esc to bring up Task Manager. Select the Performance tab.

The image above shows that I have a single socket on my server and that it has two cores. However, if I go to Start and search for and select dxdiag, I see this:

So the Intel i7-4770K chip contains 4 CPUs. Or does it? Well, not according to the Device Manager. It says it has 8!

Logical Processors

To explain these variances, we need to understand Logical Processors. These are parallel threads that execute a single instruction. A CPU can handle two or more of these at the same time. Imagine a program that calculates a complex equation (e.g. a spreadsheet operation). It could process each step in a serial fashion, but by sending instructions via different channels (threads), the time taken to finish calculations is cut significantly.

In the case of the i7-4770K I mentioned above, there are four CPUs, each capable of supporting parallel operations. Theoretically, a program could make use of all 8 logical processors, but only if it’s designed to do so.

The extent to which a multiple processor such as the i7-4770K can be put through its paces is entirely up to each program, many of which still settle for a single processor. The ones that do exploit a multiple processor’s capacity are mostly games, graphics, and video apps.

Bits and Bytes

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