Black screen (no boot up) after upgrading RAM to 16GB on mid 2010 macbook pro I have a mid-2010 (core2duo) macbook pro with 4GB (2x2) RAM. I bought 2x8GB RAM Crucial 8GB Single DDR3 1600 MT/s (PC3-12800) CL11 SODIMM to upgrade RAM to 16GB. Now after replacing these DIMMs my laptop would not start up and just shows black screen without anything on it.

Both the DIMMs are fine since if I try one of the new ones with one of the old ones my laptop boots up fine and shows the correct total of 10GB RAM. But using both the news ones together seems to be causing the problem.

I have read online that 16GB is supported by mid 2010 macbook pros. Also as per the Apple support site the mid 2010 mbp supports PC3-8500 DDR3 1066 MHz while I have the new ones as  DDR3 1600 MT/s (PC3-12800). But I have read online that this should work just fine. (PC3-12800 are cheaper compared to PC3-8500 so I thought I would give this a try)
According to everymac.com your MacBook Pro probably neither supports 16 GB nor PC3-12800 memory modules. There is one exception for the MacBookPro7,1 (MacBook Pro Mid 2010 13") which supports 16 GB.

If you happen to have a MacBookPro7,1 get two 8 GB PC3-8500 modules or in all other cases get two 4 GB PC3-8500 modules.