None of the supported controllers can handle 4TB drives, and not all unsupported controllers will work in the system. If you do try a third-party card, I'd recommend Adaptec or LSI, and just know that you won't be able to use it in the "regular" storage slot (where 2950 controllers SAS 5/6 and PERC 5/6 go).   The drivers for the SAS 5/6 and PERC 5/6 should be native to Server 2012, so if it can't find drives to install to, then you likely have a PERC 5/6, which does NOT support non-RAID - you must first configure RAID before any drives can be seen.   Don't use RAID 0. Period.
We have 2 new Seagate SAS 4TB drives and a donated (wiped clean) PE2950 (SAS).  What controller should I get to accommodate the larger drives.   I tried to install 2012 Server Essentials and didn't get very far (asked for a driver).  I'd like to do RAID and I'm leaning toward RAID0 but am open to other ideas such 2012 virtualization. Thanks! Gary Service Tag  
New SAS controller for a PE2950 for 4TB drives