Often, the first things which come to mind when thinking of upgrading your computer are either adding more memory modules (RAM) or going for a faster processor (CPU). The main reason is that these two components form the very basic core of your machine, allowing it to store program instructions (gathered from your hard drive) and subsequently access and process these via the CPU.
So what kind of difference can you expect from an upgrade, and is it discernible enough even if its only one of these components? Firstly we will find out exactly what each of these does on your machine, and eventually determine the difference in performance which can be achieved by an upgrade.
Random Access Memory (RAM)
As briefly stated in the previous paragraphs, RAM is the area of your computer which stores information required by your operating system, games, video/audio and other programs. This information typically needs to be accessed quickly and it is possible, thanks to a processing unit (i.e. your CPU or one present on a graphics card for instance), for any of this information to be gathered at any one time: hence the word Random” in the acronym. RAM is also volatile, which means it will be flushed each time you turn your computer off.
This is where random access differs from serial access, where one needs to search through from the very beginning in order to access the required information. Magnetic tape is an example of serial access.
It is important to point out that RAM cannot process information but can only serve as storage. Upgrading your computer with more or larger storage RAM modules will not add more system resources for processing information or allow you to run more than one processor intensive application (as in the case of hyper-threading or a multi-core CPU).
Central Processing Unit
The CPU is the brain of your machine which gathers information, via the control unit, from your installed memory modules, and processes instructions, via the logic unit, in order to run your programs. The CPU comes with varying clock speeds, which determine the number of instructions executable per second, and many other features which allow for faster and smoother execution.
A faster-clock CPU installed in your machine will allow you to perform these calculations and instructions faster, which in practical terms means being able to quickly access programs, read memory and execute the functions within those programs. For example, in a video conversion operation (converting one format to another), the processing times will be much less if you have a dual-core processor installed. When using a program like Photoshop or Paint Shop Pro, the effects you apply to an image use processing power also.
Do I need more RAM?
You only require more RAM if your system is visibly slow or frequently use applications which store large amounts of content needing to be retrieved quickly. An example would be an audio plug-in or Virtual Instrument which stores samples in RAM and requires large amounts of memory.
A good and simple way to check is by going into your Task Manager (Hit Control + Alt + Delete) and looking at the Performance tab. If your Commit Charge is larger than your Physical memory then installing new RAM modules will help.
When considering an upgrade both components are important. Of course it isnt always possible to upgrade both RAM and the CPU at the same time, the latter obviously being the most costly. Adding more RAM to your system doesnt hurt and, if your system requires, you will certainly notice an improvement.
It isnt recommended that you upgrade one component if all the rest is terribly outdated compared. You wont notice any improvements and old technology wont be able to make use of improved/new features.