'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).'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.'DDR3' is the type (and must be the same as what your computer has).However, your system will operate at the speed of the slowest memory module. 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. This is from the crucial website which was posted here: mac-instead-of-1067mhz The only computer that is known to run a single 8gb RAM stick is the 2010 15' Macbook pro as stated here Yes your computer is capable of running 8gb of RAM but only in 2 4gb Chips. Sometimes the higher clocked RAM is more expensive but most times it's cheaper due to availability and that the actual cost to make that newer RAM has gone down in the last 3 years. THE ONLY THING THAT IS ABSOLUTELY A MUST IS THE VOLTAGE!!!! Most newer chips run on 1.2v All Macs 2010 and below run on 1.5v so you'd need to find 1.5v higher speed RAM.Ĭompanies, EVEN CRUCIAL, will sell you higher 'clocked' RAM and it will be compatible with your computer. What WILL NOT work is putting a single 8gb RAM chip into one slot. Your Mid 2009 Macbook Pro can run PC3-8500, PC3-10600, PC3-12800 (1066mhz, 1333mhz, 1600mhz) literally anything above 8500 in the PC3 format will work.Higher speed RAM clocks down, or reduces speed to match your computer capability. I don't really post that much as you can tell. Also Don't know why people are saying the ram you posted won't work, because it will.

2009 macbook pro 3 beeps after sitting