Computer Memory Types

Trying to decipher computer memory types to determine what to put under the hood in your gaming computer? It really is pretty easy unless you are trying to do some extreme overclocking and a ½ of a percent gain is a really big deal. If you don?t have enough memory or RAM as it is commonly referred to, your computer will be sluggish. However, more is only better to a certain degree. If you load up on more than enough you will only be wasting money that could have been used on other components.

What is RAM?

First, we need to understand what RAM or Random Access Memory is. In simplest terms, RAM is your computer?s temporary memory. When loading a program, playing a game, surfing the internet, your computer uses it?s temporary memory to make the program function, store information about where in the game you are (check points), etc. Anything that isn?t saved to the hard drive is jettisoned at the end of the session. This is where the Random part comes in. Once the power source is removed it loses any information that was stored to it.

Today?s computers use Dynamic Random Access Memory (DRAM). I?m not going to go into extreme technical detail here. If you want to read the technical bits on how memory works I recommend Wikipedia for additional reading on computer memory types. You may see SDRAM in references. The ?s? stands for synchronous. The thing to pay attention to is the DDR2 and DDR3 and the numbers that follow. DDR stands for double data rate. The double is achieved by transferring data on the rising and falling of the clock frequency. Basically the engineers found a way to transfer data twice as fast without increasing the clock speed. So a memory chip that runs at 200MHz will have an effective clock speed of 400MHz. This memory type would be listed as DDR-400. You will often see PCXXXX. This is the theoretical bandwidth limit of the chip. It is measured in MB/s. It was a standard published by Intel beginning with PC100 (100MHz SDRAM). It is still used today but most often you will find the memory listed with both specification such as computer memory type DDR-400 PC3200.

What's the deal with DDR2 and DDR3?

We are in the third version of DDR computer memory type. DDR2 is the second generation and yes, you guessed it DDR3 is the third generation. DDR led way to much faster memory by doubling the output. DDR2 doubles that output again by using an i/o buffer that allows the data bus to run at a higher frequency. For DDR3 engineers found a way to double it again. Now, before you go out and spend a bunch of money on DDR3 memory it is important to note that you must use memory that is compatible with your motherboard. One should also note that while DDR3 has a data transfer rate at twice the speed of DDR2 in real world applications you are not going to see that big of a difference. There are other factors that impact your gameplay. When DDR3 first emerged early tests showed that you would see a 3% difference if that between computer memory type DDR2 and DDR3. The important thing is to match your components with the most suited pairs. DDR3 is faster and the standard computer memory type now but it isn?t the best suited in all circumstances.

We should understand by now that when choosing your memory you will want to read the technical specs for your motherboard and choose the correct version of SDRAM (DDR, DDR2, or DDR3). If your gaming computer still uses DDR you need to scrap it and upgrade. The components that require DDR are no longer suitable for gaming. Once you determine if it?s DDR2 or DDR3 there will be a number after that to help you choose the right frequency. You?ll be looking for something like DDR2-800 or DDR3-1600. When you select your memory just match the numbers to what the motherboard specs say are compatible. In general terms the higher the frequency the faster the memory. For high performance computers faster is generally better and for the most part that holds true for memory. There does come a point of diminished returns. We?ll talk more about that in later articles.

Timing/CAS Latency Explained

The final numbers to look at are the timing or CAS latency. CAS latency is the time between the moment a memory controller tells the memory module to access a particular column in a selected row and the moment the data from the given array is available. In general the lower the latency numbers the better. There are articles available on the internet that show in tests that the latency of memory is much more important with Core2 and previous processor lines from Intel. With the release of the Core i7 processors Intel moved the memory controller to the processor itself. This seems to decrease to a large degree the impact of latency. AMD integrated the memory controller into the processor several years ago when it release it?s Athlon 64 line.

So what memory should I buy?

If your setup requires DDR2 memory DDR2-800 is the standard computer memory type. If you want a little upgrade DDR2-1066 is available. If you are building a new gaming computer you will want to use DDR3. DDR3-1333 has become the standard. Remember with the newer processors (Core i5, i7 and AMD Phenom II) CAS latency isn?t as big of a factor so don?t waste money needlessly for lower latency. DDR3-1066 has shown to be adequate. DDR3-1333 has become the standard though and isn?t much more expensive. DDR3-1600 hasn?t really proved to be worth the money.

For a Core i5 or Phenom II build I would recommend 4 GB of DDR3-1333. DDR3-1600 is beginning to come down in price now so it could make your shopping list if the price is right. Good brands to consider include Crucial, PNY, Patriot, OCZ, and G. Skill. You can find great deals at TigerDirect.com and Newegg.com .