The Basics Behind a Computer Processor Written by: Daniel Barros • Edited by: Rebecca Scudder Updated Jun 1, 2009 • Related Guides: Gaming Pc | Intel | CPU We next take a look at the core of your system - the processor. Take a look inside to learn a little bit more about what keeps your computer running. What is a CPU and What Does it Do? Welcome back to another exciting edition of my multi-part Rig-building series. Last time we were talking about speakers - we discussed the physics behind how a speaker works, as well as what your best choices were for buying PC speakers. We'll move back to peripherals (the mouse and the keyboard) a little later on, but for now, we need to talk about the most interesting aspect of computing - the processor. There are a lot of clever metaphors for what the processor is like - I particularly like to think of the processor as analogous to the human brain. The reason for this is because anatomically, the brain is essential to our consciousness and thoughts and is the all-around regulator for bodily processes. Some writers prefer to think of it as the heart of the computer, but at the same time, the heart's function is to pump nutrients, oxygen into organs and tissues and to pump out waste. A more apt analogy for the heart and its vessels would be the power supply, which pumps electricity into your rig to get it working. If you're not one for analogies, let's break down what the processor actually does. If you're looking for the actual innards of a processor and what each individual piece does, that is beyond the scope of this article - I would recommend Wikipedia's How Computers Work. For this article, let's talk basics - a processor (commonly termed a CPU) is a logic device that receives information in the form of data packets that need to be processed (or executed). To understand this fully, let's look at a simple process. Let's say I want to play an MP3. What we see in everyday usage is that you take your mouse, scroll over the MP3, click it twice, and off the computer goes playing your favorite tunes. Under the hood, however, what happens in a matter of milliseconds (or seconds depending on your processor speed) is that the computer takes the program you're trying to run (let's say the media player in windows) and throws it into your RAM (which we'll get into later). From that point, the computer takes the data packets in the RAM and runs them through the processor. For an easier look at this, take a look at the diagram at the bottom of the page. Once the program is running, the computer then inputs the specific data (the MP3) that you want played. In this sense, the CPU deals with program instructions (like the actual program itself) and raw data packets (like the MP3). If this sounds a little confusing, that's because the processor is a pretty sophisticated device, with a half-century of physics backing it up. In short, the CPU is best thought of as the crux of an assembly line. You input data, it outputs data in the format that you want. Interesting as the actual device is, the CPU has a long history, considering that the first chip (CPU) was developed only in 1971. Intel developed the first computer chip, the Intel 4004, and the first mainstream chip, the Intel 8080. Keep in mind that until Intel developed these microprocessors, computers existed, but they would, at least in the 1940s when they were first developed, occupy entire buildings, and could only do one task at a time - a laughable idea at a time when you can play games, listen to music, and receive an Internet call all at the same time from a home PC. Today, the microprocessor is a part of your life even if you try to avoid it at every cost. Everything from children's toys to implantable medical equipment contains a microprocessor. But for your purposes, you want a very specific class of processor. Now that you have a basic primer into how a computer actually works, let's get down to business regarding gaming PCs. As with all my previous articles, you may have noticed that very little separates a gaming PC and a high-end PC. That is because games are processor-intensive, memory-intensive applications, much like sophisticated applications. Due to their nature, games require a speedy processor above all other things. You can have a Terabyte of Ram, the video card from the year 2400, and the sound card that has inputs man has yet to discover, but if you're running that setup with a 486 processor, you're essentially adding rims and a great sound system to a car with zero horsepower. When it comes to processor buying for the PC gamer, there are two things to watch out for - the speed of the processor and the number of cores. We've come a long way since the 1970s and nothing shows that better than the fact that the best PCs out there today run with not one CPU, but with up to 4 running in parallel inside one CPU. As miniaturization gets better and better, you can expect to see PCs running with even more CPUs in parallel. The basic buying tip for buying in terms of cores for the gamer is that you need a processor with 2 or more cores. Most CPUs today have at least two cores, so do yourself a favor and future-proof your purchase for about $150 more, and get yourself a quad-core CPU. CPU speeds are measured in Gigahertz, where a hertz is a unit of frequency (1/s); logically, the more frequency a computer has, the quicker it is capable of processing tasks. However, it's also important to note the number of cores - a dual-core, 1.5 GHz processor will run better and faster than a 2.8 GHz single-core processor. In essence, you want to buy the processor that has the most cores with the greatest individual core speed. In the next article I'll show you the top 5 processors and go over some more guidelines- (i.e. hyperthreading), to buying the brain that will keep your computer running for the next two years or so.