SATA 3Gb/s is incapable of breaking 300MB/s because of its 8/10b encoding. In fact, it is incapable of even hitting 300MB/s because it is not able to hit perfect efficiency even in that. 378MB/s is a SATA3 speed. Keep in mind that SSDs tend to not hit their maximum theoretical performance.
I'd expect higher sequential read speeds than you're getting, but what you get depends strongly on the exact workload. Try using a higher queue depth and/or larger files in those tests and you'll probably then get the read performance that you want.
I am using Asus Maximus V Formula EATX LGA1155.
Has 2 black SATA 3Gb/s ports and 6 red ..i don't know if all of the red's are SATA 6Gb/s, anyways I figured which one is the 6gb/s port by looking in the BIOS (saw the DVD plugged into it and followed the Cable) and plugged the SSD into it.
After a slow boot finality got into windows, and the drivers for SSD and Storage disk (Samsung F4 HDD) started to be downloaded automatically by Windows. Did a restart and this are the new numbers :