Fujitsu 4GB (1x4GB) 2Rx8 DDR3-1600 U ECC. Internal memory: 4096 MB, Internal memory type: DDR3, Memory clock speed: 1600 MHz. Operating temperature range (T-T): 0 - 85 °C, Storage temperature range (T-T): -25 - 95 °C. Compatibility: PRIMERGY RX900 S1