It could be a chassis issue, but you need to get much more specific than that.
When the system boots, make note of ALL firmware revisions of BIOS, Controller, Backplane, etc. - everything you see at boot time.
Dell has several firmware fixes for different parts of that system ranging from Optional to Urgent.
If you have trouble reading some of the information as it scrolls by, then use a video camera or video cell phone (my iPhone takes adequate video for this purpose), upload the video to your PC, and freeze-frame through to identify all of the various versions of firmware.
It is also possible that the drive controller board is defective, but updating the firmware is an easy first step, and often solves many problems.