Hello forum. Need your help please. I would like to upgrade my Mid 2009 13 inch MacBook Pro 2.53 GHz Intel Core 2 Duo Processor running OS X 10.9.1 Mavericks (MB991LL/A) to 16GB of Ram; it currently has Kingston 8 GB (2x4GB) 1067 MHz DDR3 Ram in it. I purchased 16GB of ram (Nanya?) from a ram seller on eBay and after I installed it in my laptop I got three beeps and the operating system wouldn't load. The funny thing I was able to upgrade to 16GB of memory (Micron?) on my Mac Mini Mid 2010 with 2.4 GHz Intel Core 2 Duo also running Mavericks. Just as an experiment, I took the 16gb of Micron memory out of the mac mini and put it in the MacBook Pro and it didn't work either - got the 3 beeps and the Operating System wouldn't load. Reset the pram and got same result - 3 beeps and os wouldn't load. So I put back the 8GB of Kingston in the macbook pro and all is well. Both mac mini and macbook pro use the same type and bus speed of ram sodimm pc3-8500 1066 mhz ddr3 so just wondering why the 16gb works in my mac mini and not in my macbook pro when both are running mavericks? I really don't think it's bad ram since the ram works in the mac mini but not the macbook pro. Thanks in advance for your assistance.