An expanded article on RAM slots 2 and 4:
In modern PCs, there are multiple slots for RAM – slots labeled 2, 3, and 4. RAM (random access memory) is the main storage area for your operating system and applications.
RAM slots 2 and 4 are both used for DDR4 memory. DDR4 is a type of RAM that has been in development for several years now.
It offers faster data access than DDR3 memory, and it is also more energy-efficient.
So far, it seems that using RAM slots 2 and 4 together is not a good idea. This is because the two slots are designed to use different types of RAM modules.
If you install a DDR4 module in slot 2, your computer will not be able to use any DDR3 modules in slot 4.