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
How RAM Works | HowStuffWorks
memory - I'm upgrading my RAM, and have conflicting results from CPU-Z and CrucialScan; how many RAM slots do I have? Also, 4x4GB vs. 2x8GB? - Super User