EVGA USB 3.0 and SATA 6GB

probably, sooner or later everyone is going to carry SATA 6GB and USB 3.0, only a matter of time

USB 3.0 and SATA 6Gbps are pretty poorly implemented on the P55... there's just not enough bandwidth.

SATA 6GB on all motherboards is poorly implemented as of now.

The only SATA 6GB controller being produced currently is a Marvell one, and it connects with one PCIe (1.0 or 2.0) lane. Most motherboard manufacturers are going the cheaper route and using the single PCIe 1.0 lane which provides you 250MB/s of bandwidth shared between each drive connected to that controller.

Asus and ASRock are doing things a little better, but still not perfect. They are using a PLX bridge chip to bridge 4 PCIe 1.0 lanes into a single PCIe 2.0 lane for the controller. This offers 500MB/s of bandwidth, again shared between each drive. That still wouldn't allow you to saturate a single drive.

My advice: wait until there's a better controller available, one that allows the full 6Gbit/s per port, or wait until Intel releases a new southbridge.

X58 it should work better. I hope they come out w/ one soon.

X58 has no advantage on this case. The controller itself will only connect via a single PCIe 1.0 or 2.0 lane. A different chipset won't suddenly make PCIe faster.