Lot of 6 Kingston 4GB ECC Unbuffered RAM 1Rx8 PC3-12800E+2Rx8 PC3-10600E-Tested | eBay
1Rx8 vs 2Rx8: A Detailed Comparison Guide Between the Two RAMS
Beware of the single rank x16 RAM kits sneaked in some laptop models! The 1Rx16 modules have significantly lower bandwidth compared to the 1Rx8 variants - NotebookCheck.net News