||32 slots with optional Sun Mezzanine Kit. 16 slots on system board; 16 slots on Mezzanine. Either 1.8V FB-DIMMs (SESX2x1Z, DRST5220) or low voltage (LV) 1.5V FB-DIMMs (SESX2x3Z, DRST5440LV) are supported. All FB-DIMMs must be the same voltage. If you upgrade to LV 1.5V FB-DIMMs, you must replace all FB-DIMMs. Valid configurations are 8, 12 or 16 DIMMs of the same capacity only.Valid configurations are 8, 16 or 32 DIMMs of the same capacity only. All 16 slots on Mezzanine must be populated.