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
Single Rank vs Dual Rank Memory: Which one is Better for Gaming? | Hardware Times
Laptop DDR4 caveats - x8 layout versus x16 versus single and dual channel
Lot of 4pc Mixed 2GB 1Rx8 -2Rx8 PC2 - PC3; 1GB 2Rx16 PC2 - PC3 Laptop RAM Memory | eBay