Will a 800Mhz DDR2 work on my macbook that has a 667Mhz DDR2

Discussion in 'Buying Tips and Advice' started by Zizou91, May 15, 2010.

  1. Zizou91 macrumors newbie

    May 31, 2009
    Hi, I've been trying to increase the amount of memory of my macbook since 1Gb is really poor, but when i went to a store and i've tried to replace my current ram memory (2 memories 550mb DDR2 667Mhz) the guy who work there told me that the DDR2 800Mhz won't work on my mac because it was designed for a 667Mhz DDR2 is that true?? some friends told me that buying a greater Mhz is even better and would also work since it is DDR2 so i don't know who to believe if the guy of the store of my friend :S and can i mix a 800Mhz DDR2 and a 667Mhz DDR2 memory cards in case that i only want to change one slot of memory?

    Thanks, i really want to increase my memory, a little help would make me really good for buying the correct ram :)
  2. emiljan macrumors 6502


    Jan 25, 2010
    DDR2 800 is backwards compatible to DDR2 667 so it should work, it just won't run at 800Mhz.

    Usually when mixing two different speeds of ram it will run at the lower frequency ram speed.
  3. Zizou91 thread starter macrumors newbie

    May 31, 2009
    :O thanks a loooott!!! I'm going to the store right away :) To make my mac ultra fast :p haha thanks :D
  4. pastrychef macrumors 601


    Sep 15, 2006
    New York City, NY
    I tried a pair of 800MHz RAM in my MacBook and it didn't work. Oddly enough, the same pair worked fine in my Mac mini... Go figure...
  5. calsci macrumors 6502


    Nov 27, 2008
    They are designed to be backwards compatible. Designed mind you. They don't always work so keep your receipt just in case.
  6. miknos Suspended


    Mar 14, 2008
    Had the same problem. You have to use one 667Mhz so the faster (800Mhz) downclock at that frequency.

    I'm stuck with 3GB RAM.

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