I own a Lenovo T420 and have been running 16Gb (2x8Gb)for years now. When I initially did this 3 years ago, I did make sure I was using the latest BIOS at the time, and after putting the 2 8Gb Crucial SoDIMMS in it was recognized by the BIOS at first boot. After saving the bios, F10, I rebooted into W7 x64 Professional with no issues as well...with it recognizing all 16Gb of it. I upgraded to Windows 10 x64 Pro since then and again no issues. On both W7 and W10, I disabled Virtual Memory altogether by opting for "No Page file" and have had no issues in doing that either. Hope this helps someone.