Is your system the one listed in your profile, because according to that you have DDR4 RAM...
https://pcpartpicker.com/list/QkqF9W
Also, what software/games are you looking to upgrade your RAM to get more performance in? It's possible that you might benefit more from upgrading some other component instead.
And unless you are using specific software that can make use of more than 16GB (such as some video editing software, for example) you are probably not going to benefit from having more than 16GB for a number of years. Also, not running RAM in a matched pair will tend to result in a bit less performance, so 2 sticks of 8GB will likely perform better for you than 1 stick of 16GB and 1 stick of 4GB.
For gaming, I would expect a graphics card upgrade would do a lot more for your performance than a RAM upgrade. Most games don't benefit much from having more than 8GB of RAM still, but they do tend to to benefit a lot from having a faster graphics card.