Crucial 32GB Kit (16GBx2) DDR3/DDR3L-1600 MT/s (PC3-12800) DR x4 RDIMM Server Memory CT2K16G3ERSLD4160B / CT2C16G3ERSLD4160B at Amazon.com
OWC 32GB (2 x 16GB) PC10600 DDR3 ECC-R 1333MHz DIMMs Memory Compatible with Mac Pro Early 2009 & Late 2010 'Nehalem' & 'Westmere' Systems and Early 2009 Xserve. (OWC85MP3S9M032K) at Amazon.com
32GB (4x8GB) DDR3-1866MHz PC3-14900 ECC UDIMM 2Rx8 1.5V Unbuffered Server Memory by NEMIX RAM at Amazon.com
A-Tech 32GB KIT (4 x 8GB) for Intel SR Series SR1630GP, SR1630GPRX, SR1630HGP, SR1630HG. DIMM DDR3 ECC Registered PC3-12800 1600MHz Dual Rank Server RAM Memory at Amazon.com