Ocico PS-S21E expends 1 external eSATA interface on the PCI-E baffle of computer case from 1 SATA interface for any external eSATA equipment use. Attach 1 pc SATA 7Pin Cable to connect this baffle to SATA interface of motherboard. 

This baffle also has 2 power switches which can control power supply individually. 2 power supplies are controlled by 2 switches so as to reduce power consumption when HDD doesn't work and give longer life of HDD. You can use it to install different operation systems or operating environment and switch between them easily.