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,
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