This issue can also occur in these three cases:
1. After a reboot (Check the Uptime of your server)
2. Conflicts with RILO (Remote Insight Lights Out) (Reset RILO related services)
3. Having an old version of Firmware (Upgrade your Firmware).
The solution from HP Techsupport for HP Smart Array 5i is to uninstall HP Insight Diagnotics using Add/Remove Programs and apply the latest Support Pack (7.30a).
According to HP, this issue affects Smart Array 641/642 controllers, causing drives to unnecessarily downshift to slower speeds. A firmware upgrade to version 2.26c should resolve this issue.
Note: To install this firmware upgrade, you should first upgrade your Smart Array controller to version 184.108.40.206. See the link to “HP Support ID 21465” for additional information on this event.