CMS 4GB (2X2GB) DDR2 5300 667MHZ ECC FULLY BUFFERED DIMM Memory Ram Upgrade Compatible with Apple® Mac Pro Quad Core 3.2Ghz Fully Buff For Server Only - B55 - Newegg.com
Fully Buffered DIMM - Wikipedia
Servers - Fully Buffered: 512MB 800Mhz PC2-6400F DDR2 240-Pin FBDIMM Fully Buffered ECC RAM Server Memory Module - CPU Medics
4GB Kit (2x2GB) Fully Buffered DDR2 Server Ram/Memory. PC2-5300 667MHz DDR2 DIMM ECC (Fully Buffered) 240 Pin 1.8V at Amazon.com
4GB 2 X 2GB PC2-5300F 667MHz 240 pin DDR2 SDRAM ECC Fully Buffered FB DIMM Server Low Power Memory for HP Workstation XW8600 (PARTS-QUICK BRAND). Equivalent to HP Part Numbers: 397413-B21, 442823-B21,