I believe you're using Intel Matrix Storage. The answer to your question will be Yes and No. Yes you can have an array grater than 2TB, but it will be data volume only, meaning you won't be able to boot from it. It is documented here: http://www.intel.com/support/motherboards/server/sb/CS-031158.htm. The reason is that to boot from a GPT disk (only GPT disks support volume > 2TB), the firmware needs to support EFI boot, which is not currently available with Intel Matrix Storage.
The workaround is to create a small RAID volume (like 100GB), make it a MBR disk, and install your OS on it. Then create a second RAID volume using the remaining capacity (GPT) to store your data.
If you really need to boot from a GPT disk you may need a hardware RAID controller. there is a step-by-step instruction here: http://www.intel.com/support/motherboards/server/sb/CS-031158.htm
Thanks for the answer...
Do you know if intel is planning on adding this efi feature in the future to this product or is this something that will be restricted to "new" products. ?
My solution will be to opt for 3 pcs 1TB drives instead and making a 2TB raid 5 array. This is actually enough and i dont fancy fiddling around with multi partitions on RAID or buying extra raid controllers.