DDR2 240-pin Memory Module

One of the most common mistakes when building or upgrading a computer is the memory. What type? How many pins? What speed? Registered or unregistered? Single or dual channel? Any skilled computer expert can tell you the answers to these. I'm going to show you how to do this yourself and how to save money at the same time.

Identify your current memory - One way to upgrade your computer's memory is to identify what is currently installed. I use a program called CPU-Z to do this. When you first open the program, be patient while it collects information about your computer. Once it has finished, view the Memory tab for a general overview about your RAM. Take note if your Memory is Single or Dual Channel (top right field).

The next tab to the right, SPD, will give you a breakdown of each individual module. The first thing to notice is the very top line, mine says DDR2. That's the type of memory. Next is module size. If you are replacing your memory, this is not important. Max Bandwidth is the speed of your memory, mine says PC2-6400. The program will also identify if your memory is registered/buffered. My values for registered/buffered are blank, which means I have unregistered/unbuffered memory. Otherwise, I would have to purchase registered/buffered memory.

The last thing to identify is the pin count or physical size of the RAM. Basically, you have two sizes for each type. Normal desktop size and laptop size. For my upgrade, DDR2, there is a 200-pin laptop module and a 240-pin desktop memory module. While laptops always use the 200-pin, you may want to double check your desktop. Certain desktop motherboards, especially those in smaller form factor systems, actually use the 200-pin style.

There are still two pieces of information missing, maximum memory and fastest speed supported by my computer. If I order more memory than my computer supports, the memory is not going to be compatible with my computer. Furthermore, while I could order memory the same speed as the current memory, there may be faster memory available. This faster memory would directly increase the speed of my system. But before we can solve these problems, we need to identify our motherboard.

DDR2 200-pin Memory Module

Identify your motherboard - To find your motherboard model number, open CPU-Z again. Navigate to the Mainboard tab and write down the Manufacturer and Model. Mine is a Dell 0GM819. A quick google search will reveal the motherboard specifications. Most motherboard specifications will flat out tell you everything, completely eliminating the need for using CPU-Z. Unfortunately, OEM motherboards can be vague. For instance, the only specification published about my motherboard regarding RAM is "4 Dual Channel DIMM Support for up to 8 GB of DDR2 memory".  Fortunately, this has revealed the overall maximum amount of memory my computer supports. However, I still have not identified the fastest speed supported by my motherboard. While I could very easily order less than or equal to 8GB DDR2 240-pin PC2-6400 Unregistered/Unbuffered Dual Channel RAM at this point, I may be missing out on faster memory modules which would improved the speed of my computer.

If all else fails (or how you should really be doing this) - If you still have missing information, such as the fastest speed supported by your system, there is one last method. Go to Crucial.com and use the drop down boxes to select your system. It will bring up a page much like this one. Find the section titled `Manufacturer Specifications`. The speeds supported by your motherboard will be listed in the box on the left. Apparently, my motherboard supports PC2-8500, PC2-6400, and PC2-5300. Had I not checked, I would not have ordered the fastest memory available for my computer.

To be completely honest, I always use Crucial.com to identify memory, and suggest you do as well. However, don't purchase memory directly from Crucial.com. Usually NewEgg and other online electronic stores sell it for much cheaper. While the CPU-Z method explains each aspect of the memory module, it takes more time and requires additional research. But now that you understand all of the factors involved with memory, use Crucial.com confidently, instead of fooling around with google searches and motherboard manuals.

How to purchase - After identifying your memory, head over to your favorite online electronic store and search. Based on our research, my search query would be `DDR2 PC2-8500 240-pin`. You can refine the search by including the size, such as 2GB. Before purchasing, make sure the memory module meets your computer's Single/Dual channel and Registered/Unregistered requirements. Good luck!

A warning regarding 32-bit memory limits - If you are running a 32-bit operating system, the maximum memory your computer will support is 4GB. You can install more without a problem, but your computer will not utilize it. In order to support more than 4GB of memory, please switch to a 64-bit operating system.