I had your X7DWA-N, when I creates a RAID level 5 array with the on-board SATA controller using four 1TB drives the systems only detects 2TB. Is there any tweak or special setting to allow him the system to see the correct array size?
The Intel ESB2 south bridge SATA RAID controller is limited to 2TB. The only option for more storage is to use a third party PCI SATA RAID controller such as 3ware, LSI or Adaptec.