3 Replies Latest reply: Jul 26, 2009 5:09 PM by stedman1
dcains Level 1 (0 points)
Sorry to post such a basic question, but after searching, I'm getting conflicting info. My MacBook 4.1 has the 2.1 GHz processor and a Bus speed of 800 MHz. It currently has 667 MHz RAM installed, but I'd like to know if it will properly work with 800 MHz RAM (i.e. 2 x 2GB DDR2 800MHz PC2 6400)? Some sites say 667 and others say 800 MHz, but I thought the RAM should match the Bus speed. Any advice would be most appreciated.


MacBook 2.1 GHz, MacBook Pro 2.33 GHz, Mac OS X (10.5.7)
  • GfulDedFan Level 4 (3,315 points)
    The answer is maybe to the 800MHz PC2-6400. I've read a lot of cases that when a kit is installed, one works, the other works, but both don't.

    You should really use the recommended or specified 667MHz PC2-5300. Here's Apple's take from your manual:

    +Both memory slots can accept an SDRAM module that meets the following+
    +- Double Data Rate Small Outline Dual Inline Memory Module (DDR2 SO-DIMM) format+
    +- 1.25 inch or smaller+
    +- 512 MB, 1 GB, or 2 GB+
    +- 200-pin+
    +- PC2-5300 DDR2 667 MHz Type RAM+
    +For best performance, fill both memory slots and install an identical memory module in+
    +each slot.+

  • dcains Level 1 (0 points)
    Thanks for the advice, but I'm still unsure about what is correct - guess I'll call Apple and see what they say for this specific model of MB. When I look at the recommended RAM for every other MP or MBP, the RAM speed seems to always match the bus speed, so I'm wondering why in this case the RAM speed should be different (and slower) than the bus.

    FWIW, this MB doesn't have its original RAM installed, it's got Kingston 2 x 2GB 667MHz RAM, and it works fine. I just wanted to know if replacing that RAM with the 800MHz equivalent might yield better performance, as RAM is so inexpensive it might be worth the upgrade. I can swap the 667MHz RAM into my wife's MB, which only has 2 x 1GB 667MHz RAM factory-installed.
  • stedman1 Level 9 (67,790 points)
    Hi dcains: From most reports on here, your McBook will NOT work with the incorrect spec RAM installed.