DDR5 motherboards should come with only 2 dimm slots as standard

DIMM slot locations DIMM slots are numbered sequentially for each processor DIMM slot locations

DIMM slot as standard DDR5 DIMMs This figure is reproduced, with permission, from JEDEC document , Figure 2 Under the hood

dimm 2 slot 2 x DIMM, Max 16GB, DDR3 Non-ECC, Un-buffered Memory; New UEFI BIOS & USB Features: 3x slot, Realtek Ethernet 23,600৳ 24,800

dimm slot Lane x8, slot x16 2UEER PCI-E PCI-E Low profile, half length Low profile, half length Lane x4, slot x16 Lane