Hardware RAID, which means buying a RAID card, and installing it in your computer is good.

Software RAID is low performance, but it’s reasonably stable, and pretty reliable.

“Onboard” RAID, which is the crappy RAID emulation built into your motherboard, has low performance, AND low stability.

I have used onboard RAID before, and I have always regretted it. You gain nothing, zero, zip, from using built in RAID emulation, no matter how much you paid for the motherboard. There is no optimization, there is no performance increase. Lose a drive in a RAID 5…It can take literally DAYS to rebuild it. Likewise checking an array for errors, and errors WILL happen, because it’s not reliable.

If you use software RAID emulation, at least you can put the drives in another machine and have a good shot for recovering the RAID. With an onboard RAID emulator? Impossible.