Can I use DDR3 1600MHz RAM in a Mac instead of 1067MHz? I'm trying to get a 16 GB (2x of 8 GB) RAM to boost my computer, even though Apple says that it's only 8 GB on macs, but we know Apple is wrong on that. However, when I searched the online shopping place, they only have 1600 variants.

Can I use DDR3 1600 RAM sticks in a 1067 Mac? …and what are the consequences? and when you buy a RAM, does the PC3-8500 things matter or not?

Hardware Specifications:
MacBook Pro 13″ mid-2010 running OS X 10.9.1 Mavericks
Running on 2.4GHz Intel Core 2 Duo
Currently have 4 GB installed (2x of 2 GB) that is DDR3 1067MHz PC3-8500
You could add the 1600 MHz memory for your MacBook Pro even though it's designed for a slower memory (1066 MHz) - it ought to work, but you'd be better off buying from a place that accepts returns. Here's some relevant information from Crucial on memory speeds (emphasis mine):


  Memory is designed to be backward-compatible, so generally speaking, you can safely add faster memory to a computer that was designed to run slower memory. However, your system will operate at the speed of the slowest memory module.


In "DDR3-1600 PC3-12800"


"DDR3" is the type (and must be the same as what your computer has)
"1600" is the data transfer rate per second specified in millions (the technical term is "clock frequency") - "1600" here means it supports up to 1600 million transfers per second - in your case, it will be slowed down to 1066 million transfers per second since that's what your Mac is designed for
"PC3-12800" is the name used in the memory industry - 12800 indicates a peak transfer rate of 12800 MB/s (of course, the actual performance in your case would be brought down to 8533 MB/s, matching PC3-8500).