Thinking a little more about theory, more RAM should not improve the framerate in 3D games for two reasons. First, most of the processing on a game is executed by the video card. Second, more RAM only improves the computer performance if there is a very little amount of memory for the program the CPU is running and the processor have to use the virtual memory feature, swapping memory data with the hard disk drive or SSD.
In our tests, all the tested games ran with no problems with “only” 4 GiB. In some games, it seems even to run with more fps with 4 GiB than with more RAM. We cannot tell the reason, but we can guess that with less memory, the game do not load some features, or transfer some data to the video card, or it may be caused by simple statistic fluctuation.
We used a video card with 4 GiB video memory, and there is a possibility that, with a video card with less dedicated memory, the computer main RAM should be more demanded. Another important detail is that we used Windows 7 (SP1) in our tests. Usually, newer operating systems demand more memory, so the results could be different under Windows 8.1 or Windows 10, for example.
So, we can say that, on the games we tested and running Windows 10, on the used hardware configuration, there is no performance gain in games by installing more than 4 GiB.
This leads us to some conclusions. First, if you have “only” 4 GiB of RAM in your computer and use it to play games, there is no need to hurry to buy more; it might be a better idea to buy a new video card first. Keep in mind, however, that if you use your computer to work with video and image editing, those programs use lots of RAM and will benefit on more installed RAM.
Second, if you are building a new gaming computer on a limited budget, you may choose to start with 4 GiB if, with the cash you save, you are able to buy a better video card. This also make sense because it is easier to install more RAM later that change the video card.
To be clear, this does not mean we are saying that 4 GiB is better than 8 GiB. The “there is no such thing as too much RAM” rule is still valid, for improving the loading performance by disk caching, or for avoiding freezing due to virtual memory swapping. Besides that, more recent games or operating systems may not work well with 4 GiB.
With all this, we can conclude the ideal RAM amount for gaming performance is 8 GiB, because there is not much difference in price from 4 GiB to 8 GiB. 16 GiB is a good choice if you have no problem in spending a little more to make sure you computer will run smoothly for more time, or if you work professionally with video or image editing.