8GB KIT (4 x 2GB) for Dell Optiplex 740 745 745c 755 DT/MT/SFF 755. DIMM DDR2 Non-ECC PC2-5300 667MHz RAM Memory. Genuine A-Tech Brand. at Amazon.com
Dell OptiPlex - Wikipedia
8GB 4X2GB Dell OptiPlex 755 Series Desktop/PC DDR2 PC2-5300 RAM Memory at Amazon.com
Optiplex 755, ram - Dell Community
8GB 4X2GB Dell OptiPlex 755 Series Desktop/PC DDR2 PC2-5300 RAM Memory at Amazon.com
Refurbished: Dell Optiplex 755 A Grade Desktop PC with Intel Core 2 Duo 2.66GHz, 4GB RAM, 1TB HDD, DVDRW, Windows 7 Professional 64 Bit, Microsoft Authorized Recertified Desktop PC w/1 Year Warranty - Newegg.com
Refurbished: Dell Optiplex 755 Small Form Factor Desktop (R2/Ready for Reuse) with Intel Celeron 430@1.80GHz, 2GB RAM, 80GB HD and licensed Windows 7 Home Premium from a Microsoft Authorized Refurbisher - Newegg.com