Says here is has 12GB of RAM installed, total capacity must be much higher, this reviewed model has the AMD A10-7850K APU... and FM2+ motherboards support up to 64GB.
Lenovo Erazer X315 Review
http://www.computershopper.com/desktops/reviews/lenovo-erazer-x315
These two submodels of the Erazer X315 have other versions of the FM2 APUs, so that to me, confirms the 64GB RAM total support with 4 RAM slot, half if two RAM slots.
http://shop.lenovo.com/us/en/desktops/erazer/x-series/x315/
Edit: Says on Ironsounds source total support is 12GB but so that must be the correct info... but I still think that figure is to low to be correct.
Edit2: The Lenovo erazer X315 manual shows mobo has 4 RAM slots, so 4 slots for 12GB of RAM makes no...