Memory Module Installation Recommendation for Intel® Desktop Boards
For best memory performance, always install memory in the blue DIMM sockets if installing only two DIMMs on a board with four DIMM sockets.
If installing just one SO-DIMM on a board with two SO-DIMM sockets, always install the SO-DIMM in the bottom socket.
See the integration guide or product guide for your desktop board for the most up-to-date recommendations for installing memory modules.