I am using the Inte S5520HCR motherboard and a SROMBSASMR Raid add-in card, and the add-in card supports upt to 300 MB per second, per port. The motherboard also has built-in raid, and I am using it as well for other drives for back up. I don't know if it is a limitation per port, or for the system as a hole.
I am a little confused with a couple of answers, I think the correct answer is that it is per drive in my case whether it is the SROMBSASMR add-in or the built-in, but don't know for sure. I don't see in the specs of the motherboard that it says.
Also, I assumed that there could be a limit on the actual throughput of the drives from the motherboard itself, but hoping not. For example, originaly I had two sets of striping arrays, wtih one set as my app server, and the other as the dataserver running with vmware and in virtual servers. It was my assumption at the time that the appserver running on the one set of striped drives in a virtual server would communicate with the database server on the other set of striping drives running in a different virtual server and that doing this was maximizing on throughput, that the motherboard processer wasn't maxing out on throughput, and so the performance was only limited by the drives themselves.