Building a Computer for A+ Study Part IV: RAM

Part four in a series on the basics of building a computer to prepare for the A+ certification exams.


RAM is an acronym for Random Access Memory that is also known as volatile memory, because the data it holds is lost when the computer using it is turned off. RAM is used by the computer to store data in the form of files for processing by a computer’s CPU.
Contrary to popular belief, RAM does not have any kind of influence on the CPU performance of the computer nor does it have the power of making the CPU work faster. Basically, RAM does not increase the processing performance of the CPU. The CPU searches for instructions that are stored in RAM to be executed. If those instructions are not stored in RAM, they will have to be transferred from the hard drive to the RAM (also known as “loading” a program). So a greater amount of RAM means that more instructions fit into that memory and, therefore, bigger programs can be loaded at once.
If you want the computer to load a program and it does not “fit” in the RAM because there is little RAM installed or because it is already too full, the operating system would show a message indicating “Insufficient Memory”. This is where virtual memory comes into play. Virtual memory is a reserved area of a hard drive used as a buffer or cache that serves the RAM. It is also known as a swap (or paging) file. The files used most frequently by running programs are stored in the RAM so that they can be accessed as quickly as possible. Files used less frequently by running programs are placed in the swap file. They’re moved into RAM when required. Since accessing RAM is much faster than accessing the fastest hard drives, the more the system has to use virtual memory, the slower it operates. All of versions of Windows make use of virtual memory, but the more RAM the system has at its disposal, the less it needs to make use of virtual memory. When more RAM is installed in the computer, the probability of running out of memory and having the necessity to make a change with the hard drive swap file is smaller and therefore, you notice that the computer is faster.


Different motherboards require different types of RAM, depending on the CPU, chipset, and a variety of other factors. Current desktop motherboards use a memory module called a DIMM (dual inline memory module). Double-Data Rate Three or DDR3 DIMM memory is the most common memory type used for desktop computers today. DDR3 RAM is the newest memory protocol that supports both dual and triple channeling (as long as the motherboard supports it) and is effectively twice as fast as DDR2 RAM, which in turn was twice as fast as DDR RAM. DDR3 RAM modules may contain as much as 16GB per stick, so it’s definitely the RAM of choice if you want a lot of memory in your computer. While DDR3 RAM is a 240-pin module, it’s not backwards compatible with DDR2 or any prior memory technology.

PC Rating

The PC Rating as it refers to RAM is a measurement of the total theoretical bandwidth of data moving between the memory module and the CPU.  For example, a DDR3 DIMM module running at 1600MHz with a 64-bit (8-byte) data path is known as PC3-12800. You calculate this by taking the transfer rate of 8-bytes and multiplying it by 1600MHz, which equals to 12,800 MB/second. This means that the PC Rating for the DDR3 DIMM will be PC3-12800. It is also important to note that PC2 refers to DDR2 and PC3 refers to DDR3.

What I picked

I purchased 4GB Corsair XMS3 DDR3 1333 (PC3-10666) RAM that operates at 1333MHz.  The RAM also has a heatspreader, which dissipates heat by exposing it to cool air over a greater surface area. While you can shop for RAM based on price, you want to make sure you are getting quality RAM for your money. Corsair is one of the most popular and trusted names in computer memory manufacturing and their RAM tends to be both reliable and fast.

Leave a Reply

Your email address will not be published. Required fields are marked *