RAID is actually going to be slower. What you want is the NVMe drives, and while you can do software RAID over them, I don't recommend it, as it'll slow things down. NVMe drives are about $400 per terabyte, and the largest are the 2tb models. Your board can take 1 evidently (M.2 key, instead of the ESATA port), but I'd triple check before purchasing.
The PCIe based AIC cards are more money, and not as large 'yet'.