They can be color-coded to show which slots should be filled first for best results. The DIMM slots on most motherboards are grouped in sets or pairs and are frequentlystta.king designated A1, A2, B1, and B2. Because it specifies how memory modules should be installed to maximize performance, this labeling is essential for configuring memory in dual-channel or quad-channel modes. The motherboard's manual, which includes schematics and specifications for every part, can be used by users to find these slots.