Most computer system specifications tend to list the system memory or RAM immediately following the CPU. In this guide, we will take a look at the two primarily aspects of RAM to look at in computer specifications: amount and type.
How Much is Enough?
The rule of thumb that I use for all computer systems for determining if it has enough memory is to look at the requirements of the software you intend to run. Pick up the boxes for each of the applications and the OS that you intend to run and look at both the "minimum" and "recommended" requirements. Typically you want to have more RAM than the highest minimum and ideally at least as much as the highest listed recommended requirement. The following chart provides a general idea of how a system will run with various amounts of memory:
- Minimum Functionality: 2GB
- Optimal: 4GB
- Smooth Sailing: 6GB or more
The ranges provided are a generalization based upon most common computing tasks. It is best to check the requirements of the intended software to make the final decisions. This is not accurate for all computer tasks because some operating systems use more memory than others.
Note: If you inted to use more than 4GB of memory on a Windows based system, you must have a 64-bit operating system to get past the 4GB barrier. More information can be found in my Vista an 4GB of RAM article.
Does Type Really Matter?
The type of memory does matter to the performance of a system. There are two basic types of memory currently used: DDR2 and DDR3. DDR is still available, but unlike to be installed in any currently sold PCs. Beyond the type of memory, each memory type also has a related speed to that ram as well. Below is a chart detailing the order of the type and speed in order of slowest to fastest:
- DDR2 400 MHz or PC2-3200
- DDR2 533 MHz or PC2-4200
- DDR2 667 MHz or PC2-5300/PC2-5400
- DDR3 800 MHz or PC3-6400
- DDR2 800 MHz or PC2-6400
- DDR3 1066 MHz or PC3-8500
- DDR3 1333 MHz or PC3-10600/PC3-10666
- DDR3 1600 MHz or PC3-12800
These speeds are all relative to the theoretical bandwidths of each type of memory at its given clock speed when compared to another. A computer system will only be able to use one type (DDR2 or DDR3) of memory and this should only be used as a comparison when the CPU is identical between the two systems. These are also the JDEC memory standards. Other memory speeds are available above these stardard ratings.
Memory Expansion
One other thing that you might want to consider is how much memory the system can support. Most desktop systems tend to have a total of four to six memory slots on the boards with modules installed in pairs (some boards now install in threes for improved performance). Smaller form factor systems typically will only have a two RAM slots. The way these slots are used can play a key role in how you can upgrade memory in the future.
For example, a system may come with 4GB of memory. With four memory slots, this memory amount can be installed with either two 2GB memory modules or four 1GB modules. If you are looking at future memory upgrades, it is better to purchase a system using two 2GB modules as there is available slots for upgrades without having to remove modules and RAM to increase the overall amount.
