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  1. #1
    New iMac - Memory speed

    Member Since
    Jul 23, 2007
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    10
    New iMac - Memory speed
    Just ordered a new 24" iMac.

    Was gonna get 3rd party Ram upgrade to 4GB but crucial have got two speeds available - 5300 667 and 6400 800 - the latter being very expensive!

    Questions
    - Any difference in real world performance?
    - Any way it can mix two different types?
    - 4gb of 5300 667 or 2 gb 6400 800?

    Cheers

    Tim

  2. #2
    New iMac - Memory speed
    Sennec's Avatar
    Member Since
    Jun 16, 2007
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    Get the 800, it's much faster.

  3. #3
    New iMac - Memory speed

    Member Since
    Apr 19, 2007
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    20" iMac Core 2 Duo 2.16Ghz, 500GB HDD, 1GB RAM, 128MB ATI Radeon X1600
    Quote Originally Posted by Sennec View Post
    Get the 800, it's barely faster.
    I fixed your post.

  4. #4
    New iMac - Memory speed
    Sennec's Avatar
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    Quote Originally Posted by smurfy View Post
    I fixed your post.
    Ty :')

  5. #5
    New iMac - Memory speed

    Member Since
    Mar 30, 2004
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    12" Apple PowerBook G4 (1.5GHz)
    Get the 667. The 800MHz memory won't run any faster at all in an iMac.

  6. #6
    New iMac - Memory speed

    Member Since
    Aug 10, 2007
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    Quote Originally Posted by technologist View Post
    Get the 667. The 800MHz memory won't run any faster at all in an iMac.
    I beg to differ:

    * 2.0GHz or 2.4GHz Intel Core 2 Duo processor, or 2.8GHz Intel Core 2 Extreme processor
    * 4MB shared L2 cache at full processor speed
    * 800MHz system bus
    * 1GB (one SO-DIMM) of PC2-5300 (667MHz) DDR2 memory
    * Two SO-DIMM slots support up to 4GB
    Taken DIRECTLY from the Apple site, specs of the latest iMac. I'd bet you 100 that the reason Apple load them up with 667 ram, is due to the (currently) prohibitively expensive 800 ram.

    Crucial list PC-6400 on their upgrade site for iMac:
    http://crucial.com/uk/store/listpart...h%29%20MA876LL

    So if it was no faster, then why would they do so?.

  7. #7
    New iMac - Memory speed

    Member Since
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    Quote Originally Posted by darwinism View Post
    I beg to differ:
    [...] I'd bet you 100 that the reason Apple load them up with 667 ram, is due to the (currently) prohibitively expensive 800 ram[....]
    Taken DIRECTLY from the Apple (hardware developer documentation) site
    http://developer.apple.com/documenta...inkElementID_7
    The SO-DIMMs must be DDR2-667 (PC2-5300) compliant
    Note also the block diagram here:
    http://developer.apple.com/documenta...4829-TPXREF101
    Which clearly notes that the RAM slots run at 667MHz

    Shall I PM you with my address for my 100?

  8. #8
    New iMac - Memory speed
    BlackSheep's Avatar
    Member Since
    Jul 02, 2007
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    24' Al_iMac 2.8GHz 4GB Ram 1TB HD, 15" PB 1.5GHz 1GB Ram 160GB HD, 2x30GB iPod, 2x Shuffle, Nano
    Question Huh?
    WOW!! The last post with the links confused me more than when I started reading the thread. People (well most) by Macs because there simple. Can someone please translate all the technobabble. I thought the 800MHz front-side bus meant you could run the faster 800MHz ram. If so does it actually make a difference?

  9. #9
    New iMac - Memory speed
    christm's Avatar
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    Quote Originally Posted by smurfy View Post
    I fixed your post.
    lol. i dont know the difference. but i would assume there isnt much difference between the two speeds.

  10. #10
    New iMac - Memory speed

    Member Since
    Aug 02, 2007
    Posts
    38
    You can mix the speeds, BUT, if you have two different speeds of RAM in a computer, all the RAM will be accessed at the lower of the two speeds. That said, Id go for the cheaper of the two cause you won't notice the difference.

  11. #11
    New iMac - Memory speed
    dtravis7's Avatar
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    As technologist stated, the new iMac runs at 667 Mhz. Purchasing faster speed ram will do nothing for you in any way. It will not run any faster than the bus speed of the system which is 667 Mhz. Why waste the $$$?

  12. #12
    New iMac - Memory speed
    needlewithaprun's Avatar
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    Quote Originally Posted by iNick View Post
    Id go for the cheaper of the two cause you won't notice the difference.
    Is there really no difference between the two?

  13. #13
    New iMac - Memory speed

    Member Since
    Aug 02, 2007
    Posts
    38
    You asked if there is any difference real world performance wise, I say that there isn't. Perhaps if you were buying a maxed out Mac pro for controlling a rocket ship on NASA's next space mission, then I'd go for the faster RAM. If I had to quantise the performance increase, Id say (and by no means is this based on anything other then personal experience) if you were encoding a CD in iTunes it might, if at all, finish 1/3 of a second quicker with the faster RAM.

    Besides if you mix 667 with 800, as per my last post, the speed of the 800 becomes effectively 667. Ask an expert (not the person trying to sell it to you) and they will say the same thing. So unless you replace both RAM modules you will not get the speed boost.

    Keep in mind that Apple themselves couldn't see the benefit.
    I wouldn't waste my money.

  14. #14
    New iMac - Memory speed
    bobtomay's Avatar
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    Dec 22, 2006
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    Texas, where else?
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    Specs:
    15" MBP '06 2.33 C2D 4GB 10.7; 13" MBA '11 1.8 i7 4GB 10.10; 21" iMac '13 2.9 i5 8GB 10.10; 5s & 5c
    technologist is correct (still have to spread it around tech)

    according to Apple's tech specs, the bus speed is 800Mhz only between the CPU and the northbridge, the bus speed between the northbridge and the memory is 667Mhz.

    Putting a memory chip with a speed higher than the bus speed in a machine with EFI and basically no tweaking capability on the motherboard to overclock (at least not easily) is wasted money. You will see no performance gain with them based on the clock speed. If you can find some 800 with lower latency than any 667 (unlikely) you may see a very small performance gain, but would not likely be enough to notice without running speed tests between the two of them.

    edit: have to say I do not know enough about EFI boards to even know how or even if these boards make adjustments between different latency memory.
    I cannot be held responsible for the things that come out of my mouth.
    In the Windows world, most everything folks don't understand is called a virus.

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