Quick Specs Smart Array P840 PCIe3 x8 SAS controller - Two internal x8 mini-SAS double-wide ports and 4GB of flashed back write cache (FBWC) memory - For up to 12 Gb/sec transfer rate SAS and 6 Gb/sec SATA Items you need for the FBWC: HP 96W Smart Storage Battery with 145mm Cable for DL/ML/SL Servers - 727258-B21 - 878643-001 - 750450-001 - 815983-001 HP ML150 Gen9 Smart Storage Battery Holder Kit - 786710-B21 (ML110 Gen9) ML110 Gen 9 NOTE: When additional 8SFF Drive cage is ordered and also P840 is selected then must select one separate HPE ML110 Gen9 Mini SAS P440/P840 Cbl Kit (789651-B21) ML350 Gen9 NOTE: This server has a spot for the battery under the fans, no need for a holder. It also uses this card when supplying the system with more than 24 SAS drives since it has 2 ports and the SAS card can only support 8 or 24 SAS drives (Depending on what sas controller you install).