The Dell OptiPlex 3040 Micro supports up to 16GB of DDR3L SO-DIMMs

The OptiPlex 3040 Micro is a tiny desktop — about the size of a thick book — and it takes two DDR3L SO-DIMMs for a max of 16GB. DDR3L (the low-voltage variant, 1.35V) is key here: standard DDR3 won’t work, and the voltage difference can damage the board. Stick to 8GB modules rated PC3L-12800 or similar and this little machine punches above its weight as a thin client or kiosk PC.