DESC: The Intel Portable Cache Module is required to enable write-back for your RAID configuration. When using write-back, data loss can occur if a system failure occurs before to the data cache is written to the hard drive. The Intel Portable Cache Module prevents this potential data loss by providing a battery backup for this data. With the Intel Portable Cache Module, the battery supplies power to maintain the data that is stored in the cache. The data is written to the hard drive when the system recovers.