It is odd that they do not specify PCIe 2.0. My guess is that it is only PCIe 1.0, which means 250 MB/s per lane, so 1000 MB/s total bus bandwidth. Since each SATA 3.0 port specs at 600 MB/s, and each USB 3 port specs at nearly 600 MB/s, it looks like there is NOT enough bandwidth to support all 4 ports at once. But with only two ports operating at a time, and considering overhead (I'd be surprised is USB 3 can exceed 400 MB/s), it may be good enough.