OpenSUSE Install :: How Comes Centos Has Drivers For Raid Chip

I have got a server which has a motherboard with nvidia mediashield raid built in, with Centos installed it picked up the raid 5 array that i had configured as one drive so the os install was straight forward. When i booted the netinstaller of opensuse 11.3 run though the setup, when getting to the partition setup is was picking up the three hdd as seperate drives and not one, so i got to a certain point and aborted the installation and i re run the installer, the raid status said the array was degarded or something which i knew there was nothing wrong with it as i had set it up only about 2 weeks ago and there was one drive missing aswell. So i removed the array and re configured the array and rebooted and the raid status said healthy again as it was before on centos, then i run the opensuse installer again and it went though the process again but completely stop at "Searching for linux partitions" , cursor was working fine , but nothing else was so i had to press reset.

This was my problem, i know kind of what the problem is, but what i want to know is , i thought opensuse is based on rhel same as centos but how comes centos has the drivers for the raid chip i have in my board and opensuse has not.