iMac Early 2009 RAM Upgrade..PC1066 or PC 1333?

Discussion in 'iMac' started by netddos, May 19, 2012.

  1. netddos macrumors regular

    Oct 22, 2005
    I know iMac Early 2009 only supports speed up to PC1066...but there is a chance that I might buy iMac 2011 model that supports PC 1333 speed in the future. Now I was wondering if I could just buy the PC 1333 RAM for my current 2009 model and be ok? That way when I purchase the 2011 later, I won't have to buy another RAM..

    Does anybody have experience on this?

  2. simsaladimbamba

    Nov 28, 2010
    That should work. I use 1333 MHz 204-pin DDR3 SO-DIMM RAM modules in my 2009 MBP which came with 1066 MHz modules and it works with them quite well, it even recognises them as 1333 MHz modules.
  3. rkaufmann87 macrumors 68000


    Dec 17, 2009
    Folsom, CA
    It might work however you would see absolutely no benefit. Only do it if it's substantially less expensive then the recommended RAM.
  4. Dadioh macrumors 65816


    Feb 3, 2010
    Canada Eh?
    1333MHz CL9 Working in iMac 27" i7 2009

    Just another data point. I did a lot of searching on this because I have a 2009 iMac 27" with i7 2.8GHz. Was installed with 8GB of 1066 RAM. For the i7 processor the memory controller is built into the CPU so it detects and runs at 1333 if it detects that the memory is capable.

    I found a good deal on some Corsair CMS08GX3M2A1333C9 4GB modules which are 1333 and CL9. A lot of posts suggested that the CL9 would be a problem since the original RAM is CL7. I bought them anyway and installed them no issues whatsoever. Ran Memtest overnight and they have been running solid for a couple of days now. Can not guarantee it will work with everyone but in my case it works great. For reference Geekbench scores rose from 8550 to about 8650 (going from memory... no pun intended). So not really worth it if you had to pay extra for 1333. But if you get a good deal it doesn't hurt.

    I was concerned that many of the people stating "CL9 will NOT work" had not actually tried it but were stating it based on the default CL7 timing of the original 1066 RAM. I would modify the statement to say at the very least "CL9 CAN work" or even "CL9 WILL work".
  5. diafebus macrumors newbie

    Apr 30, 2012
    Hey I know its been a while, but I decided to go for the 1333Mhz ram Option on my late 2009 iMac and it worked fine, and it reads it as 1333 :D

    but I have one question, now I have 2 slots with 8gb each, can I install the 2 old 4gb at 1066mhz and still get the 1333 at full speed?
    if now what should be better 16gb at 1333 or 24gb at 1066?

  6. irnchriz macrumors 65816


    May 2, 2005
    1333 ram will only work with the i5 and i7 models.

    If you put in a mixture of speeds the memory will ALL run at the lowest speed of DIMM.

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