I have your C7x58 motherboard. On OS compatibility chart Windows 2008 R2 is supported.
http://www.supermicro.com/support/resources/OS/C7_X8.cfm
I have a LSI MegaRaid 9211-8i disk controller, since the digit 5 isn't beside the check, this motherboard won't support a Raid controller under Win 2008 R2?
The motherboard had test Windows 2008 with on-board SATA controller as IDE/Raid and Windows 2008 R2 under IDE without raid. However since you install Windows 2008 R2 OS on LSI controller, I believe it does support with LSI driver required.