8GB 4X2GB Dell OptiPlex 755 Series Desktop/PC DDR2 PC2-5300 RAM Memory at Amazon.com
A-Tech 8GB (4X 2GB) Max Memory RAM Kit for Dell OptiPlex 755, 745, 740, (MT, DT, SFF) - DDR2 667MHz PC2-5300 Non-ECC DIMM Upgrade at Amazon.com
2GB Memory for Dell OptiPlex 755 DT/MT/SFF/USFF DDR2-800 PC2-6400 Desktop DIMM RAM (PARTS-QUICK Brand) at Amazon.com
A-Tech 8GB KIT (4 x 2GB) for Dell Optiplex 740 745c 755 DT/MT/SFF 760 DT/MT/ SFF 760 Series (Desktop Mini Tower and Small Form Factor) DIMM DDR2 Non-ECC PC2-6400 800MHz RAM Memory at
Dell Refurbished OptiPlex 755 Desktop Intel Core 2 Duo 2GB Memory 160GB Hard Drive 755 SFF-0430 - Best Buy
Restored Dell OptiPlex 755 SFF Desktop PC with Intel Core 2 Duo Processor, 4GB Memory, 1TB Hard Drive and Windows 10 Pro (Monitor Not Included) (Refurbished) - Walmart.com
Solved: OptiPlex 760 memory upgrade? [small form factor] - Dell Community
Restored Dell OptiPlex 755 SFF Desktop PC with Intel Core 2 Duo Processor, 4GB Memory, 1TB Hard Drive and Windows 10 Pro (Monitor Not Included) (Refurbished) - Walmart.com