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
What-is-my-RAM-type-1RX8-OR-1RX16 - English Community - LENOVO COMMUNITY
LOT OF 3) 2GB 1Rx16 PC3L-12800S & 1) 2GB 1Rx8 PC3-10600S LAPTOP SODIMM HYNIX OEM | eBay