Thanks for your question. If you are using quad ranked RDIMM's, then they can only go up to 1067mhz.  This is from the manual, page 108: ftp://ftp.dell.com/Manuals/all-products/esuprt_ser_stor_net/esuprt_poweredge/poweredge-t310_Owner%27s%20Manual_en-us.pdf Your system supports DDR3 registered DIMMs (RDIMMs) or unbuffered ECC DIMMs (UDIMMs). Single and dual-rank DIMMs can be 1067- or 1333-MHz, and quad-rank DIMMs can be 800- or 1067-MHz. Regards, 
Hi there, I own a T310 with Xeon E3450, with 4 x 4GB 1333mhz RDIMM i bought 4 x 8GB 1333mhz RDIMM and the system doesn-t start, it says that the memory installed is not usable, check DIMM configuration pleasee don-t tell me that 8GB 1333mhz RDIMMs are not supported, because the manual doesn-t say anything about that the DIMM configuration that i set up was quad rank, 1-2-3-4 slots used, with 5 and 6 not occupied thanks.
DELL PowerEdge T310 4 x 8GB 1333mhz Memory not usable