Amazon.com: OWC 48GB (6 x 8GB) PC8500 DDR3 ECC-R 1066MHz DIMMs for 8 Core or Better Mac Pro Early 2009 & Late 2010 'Nehalem' & 'Westmere' Systems & Early 2009 Xserve (OWC85MP3S8M48GK) : Everything Else
OWC 24GB (3 x 8GB) PC8500 DDR3 ECC 1066MHz DIMMs Memory Compatible with Mac Pro Early 2009 & Late 2010 'Nehalem' & 'Westmere' Systems and Early 2009 Xserve (OWC85MP3W8M24K) at Amazon.com
Samsung DDR3-1600 16GB ECC/REG Samsung Chip Server Memory (M393B2G70BH0-YK0) at Amazon.com
Amazon.com: OWC 2.0GB DDR3 ECC PC10600 1333MHz DIMM Memory Upgrade Module Compatible with Mac Pro 2009-2012 (OWC1333D3ECC2GB) : Everything Else