This 32GB RAM is 100% compatible with the Fujitsu Primergy TX300 S6. Your server has 18 memory slots, with 9 slots per CPU. To achieve good system performance, it is advisable to distribute the memory evenly across the memory slots and evenly across the CPUs. When populating with 3 identical modules per group of 3 slots and filling all slot groups, performance under peak loads can be up to three times faster than with a single module in the group of 3 slots. The different groups of 3 slots do not need to have the same capacities. If more than one CPU is present, the memory should be configured identically per CPU (mirrored to the other CPU). Only the memory slots where the respective CPU is present can be used.