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How many ram slots?

3807 Views 14 Replies Latest reply: Dec 20, 2009 2:17 PM by nicholaspe RSS
nicholaspe Calculating status...
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Dec 17, 2009 1:25 PM
My i5 should be here soon (whatever that means, and assuming the screen isn't cracked or flickering!). I know it has four slots, coming standard with a 2x2 set up. So I still have two slots to play with.

Does it make a difference how I distribute additional RAM in those slots? I would like to bump up to 8 gigs total at this point. However, I may decide to toss another 4 in down the road. I have heard that you should always put equal sticks in the slots (for some reason). Is this true or can I safely purchase a 4 gig stick to place in the third slot for now and leave the other slot available in case I decide to add in the future?

Any more savvy recommendations are welcome.


imac i5, Mac OS X (10.6.2)
  • jamesholden Level 3 Level 3 (710 points)
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    Dec 17, 2009 1:59 PM (in response to nicholaspe)
    It's best for performance to keep them matched as the system can split the load equally between all sticks.
    iMac 24", MacBook, Mac OS X (10.6)
  • Kappy Level 10 Level 10 (221,190 points)
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    Dec 17, 2009 2:01 PM (in response to nicholaspe)
    Four slots accommodating up to 16 GBs of RAM. Your user manual will provide information on installing RAM. RAM should be installed minimally in pairs. Please read the user manual thoroughly so you need not ask questions here that are explained in the manual.

    All the technical details will be provided in the tech specs for the computer which you can download at or the same information should be provided with the specs found on the Online store.
    Mac Pro 2.66 Ghz; MBP Unibody; MBP C2D 2.33 Ghz; MBP 2.16 Ghz, Mac OS X (10.6.2), iMac C2D 17"; MB 2.0 Ghz; 80GB iPod Video; iPod Touch; iPod Nano 2GB
  • Kappy Level 10 Level 10 (221,190 points)
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    Dec 18, 2009 12:14 AM (in response to nicholaspe)
    Reasoning behind what, exactly? There's nothing we can add than what's outlined in the user manual and is in the technical specs. There are no tips or tricks about the number of memory slots or the amount of memory the computer supports. So I'm afraid i don't understand what it is you need to know but cannot find. Maybe you could be more precise about it.
    Mac Pro 2.66 Ghz; MBP Unibody; MBP C2D 2.33 Ghz; MBP 2.16 Ghz, Mac OS X (10.6.2), iMac C2D 17"; MB 2.0 Ghz; 80GB iPod Video; iPod Touch; iPod Nano 2GB
  • Kappy Level 10 Level 10 (221,190 points)
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    Dec 18, 2009 9:20 AM (in response to nicholaspe)
    Next time, then, ask the question you want answered. That wasn't the case here. What you asked is answered specifically in the manual and tech specs.

    I'm sorry that you didn't like my replies but it's not always going to be answers your prefer. Nor should you assume that "read the manual" isn't the best answer especially when you don't have the manual yet nor read it before posting your question.

    We have to direct users like you to read the manual because most of you don't. Instead they post questions here that are answered quite specifically in the documentation that came with the computer. I did not "reprimand" nor infer your question was "dumb." That was your inference simply because you did not like the reply. I've helped thousands of users and you are the first who considered "read it in your manual" an offensive reply. This says much more about you than it does about me. Keep that in mind in the future.
    Mac Pro 2.66 Ghz; MBP Unibody; MBP C2D 2.33 Ghz; MBP 2.16 Ghz, Mac OS X (10.6.2), iMac C2D 17"; MB 2.0 Ghz; 80GB iPod Video; iPod Touch; iPod Nano 2GB
  • canadaskyjumper Level 1 Level 1 (0 points)
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    Dec 18, 2009 5:54 PM (in response to nicholaspe)
    That's how I would have taken the response too.

    I myself have not read the manual, and I ask questions on these forums as an alternative to reading the manual. If you do not want to waste your time answering questions that can be answered by reading the manual then don't. Pretty simple. I felt kind of an "elitist" vibe coming from that response.

    What's that thing mom used to say? "If you have nothing...."

    btw. Read the question. ie. He hasn't received the manual yet, and this is a good a spot as any to get info.
  • Randy Pozzi Level 2 Level 2 (165 points)
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    Dec 18, 2009 6:34 PM (in response to nicholaspe)
    You do not need to install ram in matched pairs. Some previous MacBook pros could take 3GB or 6GB instead of 4GB and 8GB respectively. However, its BEST to install ram in matched pairs so they work together.My i7 iMac has maxed out matched pairs. Here is the reason:

    Most modern motherboards support dual-channel memory configurations. In brief, dual-channel technology lets the computer access each of two banks of memory on successive rises and falls of the system clock, rather than only once during the entire clock cycle. The performance gain, while not double, is significant. So, if you have only one stick of memory installed, buy a second one of the same size and type. If you have two sticks installed, buy an additional pair.

    iMac 27", 2.8 GHz QuadCore i7, 2T, 16GB, ATI 4850, MacBook pro (2), IPhone 3GS, Mac OS X (10.6.2), God bless Basset Hounds!
  • canadaskyjumper Level 1 Level 1 (0 points)
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    Dec 19, 2009 6:12 AM (in response to nicholaspe)
    So... has anyone found a decent source for some cheaper DDR3 4G sticks?
  • Rick Lang Level 4 Level 4 (1,230 points)
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    Dec 19, 2009 11:04 PM (in response to nicholaspe)
    The Core i5 and Core i7 processors have the memory controller on the die, i.e. not a part of the chip set. As has been indicated and as is explained in depth in Intel's datasheets on the Core i5/i7, best memory performance occurs if the memory sticks are installed in matched pairs. But if you want to add a single 4GB stick, you can do that. The existing two 2GB memory sticks that are already installed should be the first matched pair followed by the single 4GB stick. The memory performance of the matched pairs will continue to perform to spec with the i5/i7 (unlike some earlier memory controllers that degraded all memory performance to the lowest common denominator in terms of performance). The memory performance of the single 4GB stick will be degraded because it cannot take advantage of the dual channel access. But it will work and work reasonably well. Much of your work is going to be performed in the first 4 GB of installed memory so the slower memory often would not be noticed.
    iMac 27" i7-860 quad core W8948 2.8GHz, 2TB SATA, 16GB, ATI 4850 512MB, Mac OS X (10.5.8), iPhone 3G 16GB, Powerbook G4 1.67 GHz, PowerMac G5 Dual 2 GHz RIP
  • Big Rocco Calculating status...
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    Dec 20, 2009 9:12 AM (in response to nicholaspe)
    Nick, Great Questions, one's I surely have been thinking about also. I agree with you that manuals serve a great purpose and I always read mine, however, many times I read and think, 'what the heck does that mean though'. I come here for the answers. And yes, Kap's exchange with you was not the norm. All that being said, if the new iMac comes with 2G and 2G RAM, and I want to expand it and it will work reasonable well with a single 4G in the 3rd slot, I would probably buy the single 4G with the plan to add it's matching 4G as soon as possible. That would work right?

    Looking forward to upgrading soon to an i5 or i7.
    Maybe if I am really good, Santa will.......
    iMac 20, Mac OS X (10.4.11), Maxtor One Touch Ext HD


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