We have your X7DBR-3, and for onboard SATA RAID, we configure Intel code RAID 1, to install Win 2012, but the driver from SMCI CD or FTP does not see the array. Do you have newer driver?
This board has been phased out for a while, we don't have newer driver for Win 2012, but it should work fine with Win 2008:
https://www.supermicro.com/wdl/driver/SATA/Intel_ESB2_RAID/Windows/9.6.0.1014/