What are RAM slots?
These refer to the interface to connect RAM modules. Memory is organised in the form of banks, with one or more slots constituting a bank. Each bank has a dedicated channel to the memory controller. Many motherboards, thanks to their Northbridges, implement a dual-channel RAM mode, wherein the effective bandwidth of the bus is doubled. To use the memory in dual-channel mode, one slot in each bank needs to be fitted with RAM modules that are similar in all respects.