CMS 8GB (2X4GB) DDR3 10600 1333MHZ Non ECC DIMM Memory Ram Upgrade Compatible with Dell® Optiplex 780 Dt/Mt/Sff Desktops - A69 at Amazon.com
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Dell OptiPlex 780 SFF Pentium E5800 3.2GHz + 4GB RAM (NO HDD NO OS)
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Restored Dell Optiplex 780 Small Form Factor Desktop PC with Intel Core 2 Duo Processor, 8GB Memory, 1TB Hard Drive and Windows 10 Pro (Monitor Not Included) (Refurbished) - Walmart.com
2GB Memory Upgrade for Dell Optiplex 780 DT/MT/SFF DDR3 PC3-10600 1333MHz DIMM Non-ECC Desktop RAM (PARTS-QUICK Brand) at Amazon.com