MacPro5,1 Memory
Installation:
Memory is contained in slots on the CPU tray at the bottom of the MacPro. You can install different size SDRAM modules following the order on the 4 ram slot diagram or 8 slot diagram, depending on which MacPro.
Apple's built in Memory Slot Utility will appear if your chosen memory install order is not optimum. You can check your memory configuration any time using this utility - it is located on your startup drive inside /System/Library/CoreServices.
4 Slot MacPro 8 Slot MacPro