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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
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Dell Optiplex 755 Desktop Computer, DCNE, Intel Core2 Duo CPU E6550 @2 – Gulf Asset Recovery
OFFTEK 1GB Replacement Memory RAM Upgrade for Dell OptiPlex 755 Series (Desktop Mini-Tower and Small Form Factor) (DDR2-5300 - Non-ECC) Desktop Memory at Amazon.com