Function and Importance [Source]
Random-access memory is the storage unit in the computer that allows data to be accessed randomly and crucially, quickly. It relies on constant power being provided to it in order to function, powering off the computer will remove the stored data. In order to function, the computer will offload some essential program resources to the RAM to relieve the CPU of some work. Basically, the more RAM you have, the more things you will be able to do at a given time.
The reason why many have a misconception that adding RAM will “speed”a computer up is simple, and is not entirely incorrect – just misinterpretation of what is happening. Let’s take two identical computers, we put an i7 Skylake processor in there, SSD, the works… Now, one has 2GB of RAM and one has 8GB – take a guess as to which one will actually be functional in most programs? The desktop with the least RAM will struggle to deal with multiple resources from the programs you have open, the essential windows operations usually take up 1.5 to 2.0GB in itself – so it leaves very little headroom and as such, when opening a program or file, it will stutter and likely freeze.
RAM does have a MHz value attached to its clock speed however, the difference between 1000MHz is much less than a second in real world loading times so I don’t suggest spending a fortune on “faster” units, right now £35 per 8GB for DDR3 and £45 per 8GB of DDR4 is the rough ballpark (01/2016).
My recommendation for building is to always put 8GB RAM minimum into a build, this is essential for those wanting to play AAA games, and, for people who simply want a good office desktop it’ll provide enough headroom, so that you can have multiple applications open without the fear of freezing – in short, it’ll be of huge benefit in every type of build.
As seen above, I used the HyperX Fury DDR4 2(4GB) in my rig, it provides the 2133MHz minimum required for Skylake Z170 motherboards and enough headroom for gaming and general usage, however, I will be adding an additional 2(4GB)’s later on. In some games which are really intensive, they will require 16GB to ensure maxed settings. [Source]
In my brother’s build, I placed the same type but this time DDR3 1866MHz as compatible with his motherboard. This provides ample headroom like myself, and allows for future upgrade ability. [Source]