I recently bought 2nd hand 2x4gb for my old laptop.
The ram i got is SK Hynix SO-DiMM 1.35v 1600MHz My CPU only uses 1333 only though.
Previously i had 3Gb 1x1gb 1333Mhz and 1x2Gb 1333Mhz oth 1.5v - some preinstalled modules frome the factory of Laptop.
i was using Linux Mint on that laptop it...