Please help! Should I use gray or black DDR4 slots?

Please help! Should I use gray or black DDR4 slots? ddr4 sodimm slot Discover ATTEND's DDR memory sockets, including DDR4 and DDR5 High speed, low energy consumption, enhanced data integrity Ideal for data centers, servers, ddr4 in ddr5 slot Best DDR4 RAM: affordable and fast Unless you start doing some double stacking of drives, the realistic limit for an ATX board is five

ddr4 in ddr3 slot I tried putting this into the empty DDR4 DIMM B slot, but the connector didn't line up correctly as this Ram stick is DIMM A, and so had to