Functions of RAID Cards
RAID controller chips often come within the motherboard for some operating systems. You can also get RAID controllers as PCI extension cards. In these cases you can directly setup RAID 0 and RAID 1 in your computer. But for better actions and effectiveness you should go for dedicated RAID controllers.
Hardware RAID or RAID controllers physically controls the RAID array. RAID controllers in some sense are fully programmed miniature computers. They have dedicated processors. Depending on the method through which hardware RAID interacts with the RAID array, they are classified into two groups-- bus-Based or controller card based and intelligent external RAID controllers.