Hi! I recently got an old white MacBook Unibody from 2010. It has 2GB of RAM so I got 2x 2GB of RAM second hand to replace it with. The required RAM is: PC3 8500 1066Mhz DDR3 SO-DIMM This is what the original stick was and this are the new sticks I got: Samsung 2GB PC3 8500S Sounds correct right? It doesn't work, the Mac just beeps every five seconds, indicating no RAM is installed. I happened to come accros the exact same Samsung RAM from an old 2010 MacBook Pro at home, they give the same result. Also combining the old RAM with any of the Samsung ones gives the beeps. Is there anything I could do, or anything I should look for when buying new RAM? I thought just the form factor and speed where enough to consider.