There's a lot of different modes. Here they are (information from
http://www.acnc.com/raid.html):
RAID 0 is a striped disk array without fault tolerance. For sections "labelled" as A through P for 4 drives, for sections each, A, E, I and M would be on disk 1, B, F, J, N would be on disk 2, etc. It's not a "true" RAID array because it is NOT fault tolerant.
RAID 1 is a mirroring and duplexing array. This one mirrors one drive to another, and stripes mirrored pairs.
RAID 2 is Hamming Code ECC. Each bit of data word is written to a data disk drive. Each data word has its Hamming Code ECC word recorded on the ECC disks. On Read, the ECC code verifies correct data or corrects single disk errors.
RAID 3 is Parallel Transfer with Parity. The data block is subdivided ("striped") and written on the data disks. Stripe parity is generated on Writes, recorded on the parity disk and checked on Reads.
RAID 4 is Independant Data Disks with Shared Parity disks. Each entire block is written onto a data disk. Parity for same rank blocks is generated on Writes, recorded on the parity disk and checked on Reads.
RAID 5 is Independant Data Disks with Distributed Parity Blocks. Each entire data block is written on a data disk; parity for blocks in the same rank is generated on Writes, recorded in a distributed location and checked on Reads.
RAID 6 is Independant Data Disks with Two Independant Distributed Parity Schemes. Data is striped on a block level across a set of drives, just like in RAID 5, and a second set of parity is calculated and written across all the drives; RAID 6 provides for an extremely high data fault tolerance and can sustain multiple simultaneous drive failures .
RAID 10 is a combination of Mirroring and Striping, where some disks may be mirrored (but part of the striping array), but others may only be striped (not mirrored).
RAID 50 is implemented as a striped (RAID level 0) array whose segments are RAID 3 arrays (so it should in theory be called RAID 03).
RAID 0+1 is Mirroring and Striping, similar but different from RAID 10. In this configuration, a whole array of striped disks is mirrored as a whole.
For more information, search Google or try this:
http://www.acnc.com/raid.html
EDIT: Also, EIDE doesn't have as much bandwidth as hard disks are capable of doing in the first place, so the northbridge-southbridge bandwidth won't bottleneck disk access speed, mostly because it will already be slow anyway. However, you -might- saturate your PCI bus, but I'm not sure because I'm not entirely sure about all the numbers for the components involved for trucking data to and from the IDE card.