667mhz or 800mhz ram for Macbook Pro

Discussion in 'MacBook Pro' started by bubberguy13, Apr 29, 2008.

  1. bubberguy13 macrumors newbie

    Apr 29, 2008
  2. snaky69 macrumors 603

    Mar 14, 2008
    I don't think MBP's are able to use 800mhz ram and actually downclocks it to 667.
  3. Michael CM1 macrumors 603

    Feb 4, 2008
    Go to crucial.com and they have a little app you can download to tell you which RAM to use.
  4. nineteentwelve macrumors regular

    May 31, 2007
    Shrewsbury, UK
    You are correct.
  5. bubberguy13 thread starter macrumors newbie

    Apr 29, 2008
    well according to crucial.com, the most it can handle is 667. But, who knows, this ram is very new. the major question is whether or not the ram is clocked comp is clocked to only 667. If it is, there is no point in 800mhz.
  6. taylorwilsdon macrumors 68000


    Nov 16, 2006
    New York City
    It is. There is no point in 800mhz.
  7. Ant1-Hero macrumors regular


    Jan 15, 2008
    sure there is there is always future proofing, perhaps with the new montevina coming this summer, it may use 800 mhz, so you can slap in in a new macbook pro
  8. CanadaRAM macrumors G5


    Oct 11, 2004
    On the Left Coast - Victoria BC Canada
    Welcome to MacRumors

    Your question (along with many others) is answered under the Guides tab at the top of this window.

    Guides: Hardware: Understanding Intel Mac Ram

    All CorexDuo Macs are hardwired to 667 MHz with the exception of this week's new iMac.

    There is no advantage to 800 MHz RAM in machines with 667 MHz memory busses, and there are numerous reports of 800 MHz RAM failing in Penryn MacBook Pros.
  9. burningrave101 macrumors 6502

    Mar 4, 2008
    You may run into an issue of the laptop not wanting to boot if you install two 800Mhz modules in a new Penryn based MBP. Mine wouldn't detect my OCZ DDR2-800 modules paired together because they didn't seem to want to detect the right timings for running at 667Mhz. One stick would work though as long as I had one of Apple modules installed since timings always default to the slowest RAM. I was able to get around this by contacting OCZ and them sending me a new flash ROM to flash the modules.
  10. bubberguy13 thread starter macrumors newbie

    Apr 29, 2008
    but i think there is no point in getting the 800mhz ram if i already have the 667, unless there is some update so tht i can use the 800mhz. not to mention that the price will probably go down in the near future.
  11. burningrave101 macrumors 6502

    Mar 4, 2008
    No there would be no point in buying it now when you've already bought the 667Mhz. Only reason to buy the 800Mhz RAM is if you hadn't bought anything yet and the 800Mhz was around the same price. The next refresh of laptops may use something even faster than 800Mhz or even DDR2 though so there may not even be a point in that.
  12. OWC Larry macrumors member

    OWC Larry

    Apr 7, 2005
    Woodstock, IL
    There is zero benefit from installing DDR2 800MHZ memory in a 667MHZ Core 2 Duo MacBook Pro or any of them for that matter...

    Further - the JEDEC spec 800MHz program does NOT operate correctly in a Core 2 Duo Mac that takes the 667MHz memory.

    We are now offering the 800MHZ memory for the new iMacs and had concern when we went ahead to test that backwards compatibility. This is the case with both Hynix and Samsung original 800MHz 1GB modules that came in new iMacs we've got in testing now too.

    If you've got a 667MHz Macbook, MacBook Pro, iMac, or Mac mini - get 667MHz spec memory.

    FWIW - the Mac Pro is a different situation. There is no benefit for 800MHZ FB-DIMMs in the 667MHz spec Mac Pro models- but the 800MHZ FB-DIMMS fully backwards compatible operate at 667MHz C5 when installed into the 667MHz systems - for those looking for possible future flexibility.

    And even that said... in our experience - over 90% who buy memory for that upward mobility never take advantage of that. Either because when they do make their next upgrade, another different type is now needed or because it's just as well to keep the existing machine (or sell it as is) with the performance benefit the extra memory gives and just get new memory for the new system... especially right now with prices so low.

    My advise - save the difference and get the product that's spec for your system. Time value of money and all that stuff.
  13. bubberguy13 thread starter macrumors newbie

    Apr 29, 2008
    Awesome! Thank you for the info!
  14. burningrave101 macrumors 6502

    Mar 4, 2008
    I was under the assumption that this was a Penryn revision based issue as to why the 800Mhz SO-DIMM modules no longer detected properly at 667Mhz. In the pre-Penryn SR MacBook Pro's there were a lot of users that installed the 2x2GB OCZ DDR2-800 kit in their MBP and most had no issues. For the new Penryn MBP though I had to flash the SPD to get the correct timings so they would boot.

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