If you don’t know what kind of motherboard your computer has in it, then finding the right type of RAM memory sticks you need can be tricky. In order to upgrade your RAM, you’ll need to find out 3 pieces of information in all: what type of memory do you need; how much do you have; and how much can your motherboard handle.

To do this you either have to pop it out to take a look at it, or you have to go online and look up your computer’s specifications (as long as it wasn’t custom-built by piecing parts together) at the manufacturer’s website. However, either of those methods will only get you 2 of the 3 pieces of information needed.

Fortunately there is a third way to find this information using a software program, and it makes everything much easier. But first, here’s how to do it the manual way so you don’t have to rely on software that may not be available at the time.

1.) Manually – Find Type & Amount

When you look manually you’ll be able to do at most 2 of 3To find out what kind of RAM your computer is using you’ll need to shut it down completely, and unplug the power cable. Give it about 10 seconds to completely discharge all the stored electricity in the capacitors of the motherboard and power supply, and then you can start to open your computer case.

Inside your computer you’ll find a big circuit board that looks similar to the image at left. In the image at left, look for the letter H on the diagram – that is the RAM Slots. On each end of one of the slots there are some little tabs. If you push those at a diagonal down and away from the slot, they will unlock the stick of RAM from the board, and you should be able to easily lift the memory stick straight up off the board.

Once you have the stick in your hand, it will usually have a sticker on it, like in the image at right. (The image at right is a picture of some Laptop memory, but the concept is the same.) Somewhere on the sticker will be a alphanumeric code that starts with PC followed by some numbers. Most commonly it is PC3200. That’s only one part of the equation…there are still 2 more: How big are the memory sticks you have (and what is the total memory you’ve got over all), and what is the maximum that your motherboard was build to handle.

Hopefully there is a number in MB or GB that is divisible by 8 (for MB) or below 4 (followed by GB) somewhere on the sticker (usually 256MB, 512MB, 1024MB/1GB, 2GB , 4GB). In the image at right, the stick is a 1GB stick. If there is no size noticeable on sticker, you can try to search Google for some of the numbers on the sticker or memory stick to see if you can find out. Otherwise you’ll have to jump to method 3 below.

2.) Look up the Motherboard – Find Type & Max

The second method for finding out which memory your computer has involves doing a little bit of searching the internet for either your motherboard’s model number, or if you’re lucky enough to have bought your computer from some place like Dell or HP you may be able to find it on their website via a service number. If that’s the case, and you have a service number, you can contact support to find out what type & how much memory your computer can handle – and if you’ve never upgraded your RAM, then you can probably find out how much is in it from the original build.

We’re going to assume you’re not that lucky, and your computer was custom built with lots of different pieces. Again, we’re going to have to open the case if it’s not still open – so shut down the computer, and unplug it. After 10 seconds, pop the case off, and look around the mother board for something similar to the image at left.

The model number will be printed in the same color paint as everything else written on the board, and will be close to the maker’s name. In the image at left, the manufacturer is “Fatal1ty” and the model number is “AN9 32X”. Once you have these pieces of information, hit up the Googles and do a search…and we’re looking for either a technical article, a specification sheet, or perhaps a product listing in a computer-parts store.

I picked the first link, because the beginning seems like a good place to start. As long as the page starts talking about the technical specifications for the board, it’s probably a good place to start looking for what you need. I did a Find on the page (CTRL + F) for the word “PC”, but that didn’t turn up any results similar to the PC3200 or other numbers we’re looking for. The next one to search for is “DDR” as that is the common way the sticks of RAM are built these days.

Side Note: SIMM/SDRAM = “Single Inline Memory Module”, Chips on one side of the memory stick. DDR = “Double Data Rate”, Chips on both sides of the memory stick. (Though, these days it’s possible to stick both sets of chips on one side, as there is also such a thing as QDR (Quad Data Rate) which has 2 sets of chips on each side, totally 4 sets of chips. Unless you’ve got a very expensive gaming computer, you’re probably going to have DDR.

Choosing to search for DDR turned up exactly what I needed to know…

There are four DDR2 memory slots which accommodate up to 8GB of DDR2-800 RAM.

Now we know it can handle 8GB of memory (unless you’ve got a 64-bit operating system, you’re only going to be able to use 4GB of it).  Unfortunately they didn’t mention what PC number it is, so we’ll use the table below to find out what we need. To do this, consider the PC2100 DDR266 image at the top of the article. Under the “PC Rating”column, we find the PC2100, and right next to it in the “RAM Speed in MHz”there is the 266 (which represents the DDR number), and it says DDR in the “Type of RAM” column as well.

If you use the same method to find our DDR2-800 ram, you’ll need to look in the “Type of RAM” column for the DDR2 rows, and find the “RAM Speed in MHz” that matches 800. This results in a PC2-6400 “PC Rating”.

Assuming you were able to find out how much memory you have in your system already, we now know how much the motherboard can handle, what type it takes, and how much we have/lack. You can use this PC2-6400 “PC Rating” to go shopping online for more memory. Be sure you notice whether you’re buying memory for a Laptop or Desktop computer, and that you get the right one from the store. Laptop memory is shorter than Desktop memory, and as such it won’t fit in the slot.

3.) Using CPUZ from CPUID – Find Type, Size & Max

The third option is using a software program called CPUZ. Now, because I don’t like sending people to pages to download software, when those pages also include ads with huge “DOWNLOAD NOW” buttons, below is the location on the page you’ll want to actually download from:

Then click the purple download button…

During the Install process, be sure to uncheck the Ask.com toolbar stuff.

Once you’ve downloaded and installed the program (I installed mine to my Flash Drive, so I can use it on any computer) you should have a folder that looks like this:

The program is named cpuz.exe, and when you run that, it will show a loading box, and then a window with a lot of information like this…

CPUZ – CPU Tab

On this first page you’ll be able to see everything about your processor – the make, model, speeds, cache, etc. For this blog post, we’re not interested in any of that information – but do make a mental note that you can use this tool to get that info when you do need it. We’re interested in the Mainboard, Memory, and SPD tabs. First up is the Mainboard…

CPUZ – Mainboard Tab

This tab describes your motherboard – the manufacturer, model, and type of graphics card you need. This gives us 1 of the 3 pieces of information we’d need for RAM Upgrades: Motherboard Model Number. Use this to deduce the maximum RAM your computer can use. Anything over 3.25GB will go unused in a normal Windows environment. You’ll need to upgrade to Windows 64-bit, Apple OS X, or a Linux distro that can handle 64-bit. (There are a lot of other upgrades involved in this as well, like a 64-bit processor, motherboard, devices like printers, etc – so don’t do it just to have more RAM.)

CPUZ – Memory Tab

This tab describes the current state of your computer’s memory. It gives you the 2nd piece of your RAM Upgrade Equation: Current Memory. It has the “RAM Type” (DDR2 in my case), current Memory (2048MB or 2 GB), and the Frequency (332.5MHz).

As a little experiment, I wanted to see if I could deduce the “PC Rating” just from the DDR2 & the 332.5MHz values. As I mentioned before, DDR stands for “Double Data Rate”…DDR2 stands for “Double Data Rate2”. This means that while DDR operates at twice the *throughput* as SIMM (because of 2nd set of chips), DDR2 operates at twice the *speed* as DDR. In other words, for every 1 calculation that DDR can do, DDR2 does 2 calculations. What does this mean for my numbers? It means that since my RAM is doing 2x the calculations for the same amount of frequency (MHz) in order to get the effective frequency, I need to multiply it by 2.

For DDR2…

Formula: Frequcney x 2 = DDR2 RAM Speed in MHz

Equation: 332.5MHz x 2 = 667MHz

According to the table posted above, the DDR2-667MHz corresponds to PC2-5300. Let’s see if that is correct…

CPUZ – SPD Tab

According to the Max Bandwidth section, that is correct: PC2-5300 (333MHz, sometimes it gets rounded up).

The SPD Tab will show you what is in each of your slots. It gives you the 3rd piece of your RAM Upgrade Equation: RAM Type.

As you can see in the image above, this data describes the memory stick in Slot 1. There is a drop-down menu that will have a slot entry for each of the available slots on your motherboard. This tab will show you who made the memory stick, what the part number is, how much memory it has, as well as the “PC Rating” & Frequency (aka the 333 MHz portion of the Max Bandwidth). It will even tell you the week of the year it was made. In this case, it was the 39th week of 2007.

Closing Comments

Once you’ve got all 3 pieces of the equation: Max RAM, RAM Type, Current RAM, then you’re ready to upgrade your computer’s memory, and everything will appear to go a little quicker.

There is another factor in RAM upgrades that you should probably know about, but won’t prevent you from upgrading. RAM has different Frequency values (i.e. the 333MHz) on my sticks. The larger the number the faster things will move in and out of RAM, speeding up your system. However, in addition to RAM Types, motherboards also specify a maximum frequency at which they can operate. So if you find some DDR2-1600, but your board only supports DDR2-800, you’re only going to be operating at half of the RAM’s capabilities – with the motherboard being the bottleneck. So unless you’re going to upgrade your motherboard (and everything else attached to it: video card, processor, etc) don’t look for RAM with a higher frequency than your motherboard can actually use – you’ll likely just be wasting money.