I am trying to create a raid0 array using 2x Crucial C300 64gb drives. I am setting them up on my Marvell controller (my motherboard is an Asus X58 Sabretoorh) using sata 3 6gbs but its no faster in terms of read speed than the drive running on its own. Do I need to setup the array on sata 2 instead?
The Marvell 9128 6G chip on most boards maxes out at just over 400MB/s and has poor caching performance. The newest 9182 Marvell chip is much stronger but very limited in use so far. Has to do with the PCI-E 1x speed bottleneck on your board.
You'd be better off on the ICH10R if you have it available.