In the case of a motherboard with four RAM slots, it's probable you'll want to install your first RAM stick into the slot labeled 1. A second stick should go into Slot 2, which isn't next to Slot 1. If you have a third stick, it would go into Slot 3, which will actually be between Slot 1 and Slot 2.

Which RAM slots to fill first?

Fill slot 0 (or 1) first, then the other slots sequentially as you add modules. If you are installing memory in a dual-channel memory motherboard, install memory modules in pairs, filling the lowest numbered slots first.

Are there different RAM sockets?

Most motherboards have two to four memory slots, which determine the type of RAM used with the computer. The most common RAM types are SDRAM and DDR for desktop computers and SODIMM for laptop computers, each having various types and speeds.