One of the most common questions I get asked by people is: What is the difference between a hard drive and memory? This is usually in response to when I suggest that their system could use an upgrade of one or the other (usually memory). In spite of having names that reflect a similar purpose, these two computer components are actually very different.
Where your stuff is stored: The hard drive.
Think of the hard drive as your computer’s “long term” memory. All files, whether they be documents, pictures, music files, videos, or movies that are located on your computer are stored on the hard drive. Hard drives typically look like this:
A hard drive is a mechanical device. Inside the metal enclosure, there are a series of platters. These platters look like really shiny CDs. Unlike CDs, these platters are magnetic and sit on a drive motor that causes them to spin very quickly. Towards one end of the enclosure there is an arm containing several tiny magnets. This is called the read/write head. And it quickly moves over the platters to, you guessed it, read and write data to the platters. Given that these are moving parts, the only moving parts in the computer (besides fans), the hard drive is usually the slowest component in the PC. The moving parts also mean that hard drives are also the most failure prone, components in a PC. This is why it is very important that you have a good backup plan for your files.
That said, a good working hard drive can store data for a long time. Even when the computer is powered off for weeks, months, or even years the data will still remain on the hard drive. However, hard drive capacities are limited. Once a hard drive is full, files and data will need to be deleted from it before more files can be added. So, for example, if you have thousands of pictures on your PC, and it warns you that the hard drive is running low on disk space, you will either need to move some of the pictures to another storage device (like a USB flash drive or an external hard drive) or you will need to delete some pictures before putting anything new on.
So then what is Memory?
“Memory”, or more accurately RAM (which stands for Random Access Memory) is a set of computer chips that reside on a small circuit board attached to your computer’s motherboard. It looks like this:
The purpose of these chips is to help your computer perform better by temporarily storing bits of information that pertain to whatever you happen to be doing. For example, if you open a program, that program is loaded into the computer’s Memory/RAM and further actions in that program occur much quicker than they would if there was no RAM installed.
RAM is also different from a hard drive in that, if the computer is shut down, anything that was being stored in RAM is lost permanently. The only time RAM actually fills up is while the computer is running. Additionally, RAM can be freed up by closing processes and programs. In our above example, if you were to close the program you had previously opened, the RAM that was used by that program is freed and is able to be used for other things.
Commonly, the cause of a slow PC can be insufficient RAM. This means that there are enough programs running on the computer, be it programs you are using or programs running in the background, that not everything can fit in the available RAM space. In these cases, the computer will do something known as caching which means putting some of those running programs on the hard drive. This causes a major slowdown of the entire system since, because hard drives are mechanical, they perform much more slowly than RAM. The common fixes for this are disabling background programs, or adding additional RAM modules to your system. Please note that deleting things like pictures or email will NOT free up RAM. So don’t go overboard deleting files if your computer tells you it’s low on memory because that will not help.
So which one do you need?
Typically, most modern computers will need a RAM upgrade before they’ll require a hard drive upgrade. However, this all depends on the components that the system was built with, as well as what you do with the system. With the information provided above however, you should be able to much more easily determine which type of up grade you’ll require. Just remember hard drive = files, RAM = speed.