http://n40l.wikia.com/wiki/Memory
The N40L comes with 1 × 2GB ECC RAM installed. It will accept up to 16GB (2 × 8GB) 240-Pin DDR3 SDRAM 1333 (PC3 10600) RAM [1] [Does this apply to all Gen7s?]
Non-ECC RAM is compatible, but not recommended for mission critical servers. Most casual, NAS or home server systems do not require ECC RAM.[2]
Does not support registered (buffered) modules. Using registered modules will result in the server failing to POST/boot. (‘blue light’).
Capable of utilising dual channel RAM, which results in marginally increased memory speeds when two matched DIMMs are installed.[3]
Ensure that RAM modules do not have large heat-sinks protruding from the top (clearance approx. 40mm from slot to chassis).