CPU-GPU-RAM-HDD – Computer Terms Explained in Plain English


When trying to decide which laptop to buy, some choices are easy: weight, size and color.

But then come the tricky bits: processor, RAM, hard drive, graphics card… how do you know what to choose? Which features can you save on, and where should you splurge?

The Processor or CPU (Central Processing Unit) is the brain of the computer. When you type in something in Word, for example, it goes into the Random Access Memory (RAM). The CPU will take a look at it and decide if it needs to send instructions to other parts of the computer. It then assigns various tasks to the appropriate parts, and what you just typed appears on your screen. A processor is rated by its "clock speed" (GHz or GigaHertz), which indicates how many instructions per second it can handle.

Processor Example
Intel Core 2 Duo Processor T8300 (2.4 GHz/800MHz FSB, 3MB Cache).

This processor can manage 2.4 billion instructions per second; information travels at 800 million cycles per second (MHz or MegaHertz) between the processor and the Random Access Memory (RAM) ("bus speed") along the "Front Side Bus" (FSB), which is a "road" inside the computer along which information travels; it can store 3MB (Mega Bytes) of information in the Cache, which is a high-speed memory where the most recently accessed data and information is stored for faster processing.

Generally speaking, more GHz is better, but if you are using your laptop only for word processing, email and internet, you generally do not need the maximum GHz upgrade offered. The same goes for MHz, but remember that they work together, so if you have a really fast bus (= more MHz), you also need a fast CPU (#GHz) in order for your computer to work faster. If you can choose only one thing to upgrade when it comes to the CPU, go with more GHz.

When people talk about a computer's memory, it is usually RAM they're referring to. RAM, or Random Access Memory, functions like a temporary holding place and is only active when your computer is turned on. All the information you put into the computer goes into RAM before being processed by the CPU. The programs you are currently working in are also stored in RAM (for example, you don't need to start up Word again every time you go back to the program, it's there and waiting for you unless you close it).

RAM Example
3GB Shared Dual Channel DDR2 SDRAM at 667MHz.

The 3GB means that it has a total of 3GB of memory; "Shared" means it shares memory with the graphics card. This is fine for word processing, internet browsing and email, but will slow your computer down if you, for example, play online games, record music or edit videos (if you have a separate graphics card, this won't happen). "Dual Channel" means that memory is transferred to the CPU using 2 channels, which makes it faster. DDR2 SDRAM is the name and type of memory, and the MHz tells you how fast the memory travels (in this case 667 million cycles per second).

If you want your computer to work fast, this is where you need to spend some money, on more and faster RAM (i.e. more GB and MHz).

Hard Drive
The hard drive is where all your programs, drivers and other applications are stored, and also where you usually save everything you create on your computer (unless you use external hard drives, more on that in a moment). It is non-volatile, meaning that it does not need power to keep all the information there (unlike RAM). The more GB your hard drive has, the more it is able to store, but that doesn't mean it's faster. The speed of the hard drive (i.e. how fast information can be retrieved) depends on the rpm (revolutions per minute) which indicates how fast the hard drive spins. Most laptop hard drives have an rpm of 5400, but you can upgrade to 7200. The cons of a faster hard drive are that it generates more heat and will drain your battery faster, so take that into consideration when configuring your laptop.

160GB SATA Hard Drive (5400RPM).

This hard drive can store 160GB of data. The SATA is the name of the interface (i.e. the means by which information travels between the hard drive and the motherboard) and it spins at 5400 revolutions per minute. You would think a hard drive with more capacity is faster, but it is actually just the opposite. Sometimes you'll see laptops with dual hard drives, and a dual hard drive is faster than a single one. Recently, Solid State Hard Drives have started to appear, and the larger ones are a great choice if your budget allows it (128GB is currently the largest solid state hard drive available). Since they don't spin (like traditional hard drives), they are quiet, don't get hot, won't drain the battery as fast, and are much better at handling shakes and bumps.

You don't need to spend a lot of money on upgrading to a huge hard drive (just make sure you have enough space for your operating system, programs, files, etc). It's very easy, and relatively inexpensive, to add external hard drives.

Graphics Card
The graphics card produces everything you see on your screen, from plain text to complex 3D graphics. The card comes either integrated, meaning it is soldered to the motherboard, or separate ("discreet"). The integrated card shares memory with the CPU, which really slows things down if you do any online gaming, or work on music or video. Another downside is that you can't change an integrated card if you decide to upgrade. The discreet card has its own RAM and version of a CPU, the GPU, so working on complex image production won't affect the speed and performance of the rest of your computer. The speed of the card is determined by its bandwidth (i.e. how fast information travels between the GPU and the graphics memory, or RAM).

The fastest cards are capable of producing up to 60 3D images per second (the human eye can only see 25/second, but more are needed to make a 3D game flow smoothly). If you are using your computer only for word processing, email and internet browsing, any of the newer laptops will do the trick with the card that's included (even if it's integrated). If you want to do more graphics intensive work (like in Photoshop or Illustrator), a separate card is preferable. And if you use your laptop for online 3D games, you would want to go with the best card your budget allows; one that is separate from the motherboard, has a lot of memory and a fast processor.

128MB NVIDIA® GeForce® 8400M GS

This card from NVIDIA has 128MB of RAM, GeForce is just a name, and 8400M GS is the model number. Most computer sellers only list this kind of basic information about the graphics cards. To get the full specs on any card listed for a computer, you need to go to the manufacturer's website.

A new computer is a big investment, and all the options can be overwhelming. I hope I have helped you narrow down which features are most important to you, and that you feel a bit more confident when configuring your next laptop or desktop.

Author – Cattie Coyle writes about pink laptops and helps you figure out which one to choose.

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Comments on CPU-GPU-RAM-HDD – Computer Terms Explained in Plain English Leave a Comment

June 28, 2010

Andraeseus @ 7:39 pm #

you are awesome. you totally broke that down in lamens terms. question though. why do they rate processors and and fsb's in frequencies and not in what we all care about ie: How much data can this thing move and process per second? it makes me no difference about the MHZ if it doesnt move an equally impressive amount of data at the same time

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