Many NAS from Synology, and especially in certain ranges, they have the possibility to expand their RAM, even if it’s not particularly supported. One of the differences between two models such as the DS1515 and the DS1515+ is that the second one supports up to 6 GB of RAM through an accessible SODIMM slot on one of its sides.
The DS1515 comes with 2 GB of RAM, an interesting amount for a NAS. The best part is that the 2 GB of 1600 DDR3 RAM are mounted on a SODIMM slot. We can mount up to 4 GB of 1600 DDR3 in this slot as long as they are low voltage, therefore 1.35 modules. The only difficulty is that we need to gain space between the NAS’s motherboard and the storage slots so that we can extract the old module and install the new one. Unmounting it will oblige us to almost unmounts the whole NAS, because of the connection “riser’s”, so it’s best to just make some space to be able to unblock the installed DIMM and replace it for a new one.