Which version of SBUU are you using?  You should be using SMTD (Systems Management Tools and Documentation) version 7.2 or later, not SBUU.  Have you tried installing directly from the Windows media?  What is the EXACT message you are receiving?  Note that the oddball chipset of the 2970 will most likely require you to load the driver during the install if using a CD/DVD drive.  Installing from USB will avoid that scenario.
Hello Everyone, I am trying to install Windows Server 2012 on a Power Edge 2970.  I am using the Dell System Build Update Utility follwed by the Dell Windows OS Install Support Pack but then when I get to the Server 2012 media install it loads but then throws a missing driver error.  Install can not proceed. Can someone please provide any suggestions or ideas?  I have 2008 R2 Server currently running on the Dell Power Edge 2970. thanks Ron 
Installing Server 2012 on Dell Power Edge 2970