Model A1225 / Mid 2007 and Early 2008 / 2.4, 2.8, or 3.06 GHz Core 2 Duo processor

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Upgrade memory to 8GB

I have an iMac 3.06GHz, EMC No. 2211.

It currently has 4 GB memory. I have read that unofficially it can be upgraded to 6 GB (4 GB + 2 GB). I just wish to know if I can upgrade to 8GB (4 GB + 4 GB).

I have already referred to the IFixit upgrade page. It just says that the maximum memory is 4GB. I just cannot recall where I read that it can be upgraded to 6GB. I am just wondering if it can go to 8 GB since it has 2 slots

But in iFixit it also says that "Although 8 GB will physically fit, the system will be unstable if 8 GB is installed." So should I upgrade to 6 GB only?

Contestado! View the answer Yo también tengo este problema

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From my experience going to 6Gig is workable on this system. Going to 8 is very risky.

So far I've found the slower clocked CPU based systems work better than the higher clocked CPU's of this model line when pushing the limit to 8gigs. I suspect the controller logic runs into trouble with the higher lines it has to read on faster CPU based systems. In any case its not worth the hassle so I stop at 6gig when upgrading any of this model line

Referring to the following pages you'll see Apple doesn't support more than 4gig and many third parties likewise stop there as well.

Apple has updated their spec sheets before when newer memory chips or firmware updates allowed more memory to be supported. Then again, timing is everything. As this is such an old system Apple may have decided not to update the spec sheet (remember they need to do a lot of testing before they bless more memory per a given system). So these sheets could be very dated and Apple never took the time to do the testing hence the sheets show the limit is still 4gigs yet 6gigs work and 8gigs is going too far due to hardware limits (memory controller on faster CPU based systems).

Apple:

iMac (Mid 2007): Memory Specifications

iMac (Early 2008): Memory specifications

Crucial: search for: 4GB kit (2GBx2) DDR2 PC2-6400 Unbuffered NON-ECC 1.8V

Just to be clear the Intel Support logic can only address 6 GB of RAM (limit of address lines) So you can use either 6 GB of RAM or you can use in some systems 8 GB of RAM but only the base 6 GB will be used.

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Thx Dan!

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Yes this machine will run 2 - 4GB chips for a Max RAM of 8GB.

Update: but only 6GB can be accessed.

If this Answer is helpful please remember to return and mark it Accepted.

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What kind of ram did you use?

Could you post a link or specifications please?

Thanx a lot

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See above - You can only upgrade to 6GB on this system.

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It's not an Apple issue; it's an issue with Intel's supporting chipset for the CPU. You can install 8GB, but the CPU will only address 6GB; the last 2GB is a total waste. The same thing happened with the late 2006-early 2007 generation iMacs/laptops; you could install 4GB, but it would only address 3GB. Apple wisely refused to install unadressable memory on build-to-order systems, as that was a waste of customers' money. Sadly, the rest of the PC industry was happy to scam their customers by charging for memory the computers couldn't use. Fortunately, that issue has not reoccurred since the replacement of DDR2 RAM with DDR3 RAM. If you have a Unibody laptop or a 2009+ iMac, you can install matching sticks of high capacity (8/16/32GB, depending on the system).

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I have a mid-2007 iMac 24 2.4Ghz with El Capitan. I previously had 3Gbs installed then I went to use 6 (4+2), it worked well... Now I'm 8Gbs(2x4) and it works well either. The difference I have with (2+4) and (4+4) is that in (4+4) you use only 6Gbs but you have dual channel enabled!!! No issue noticed so far...

Cheers...

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Quick question when upgrading to el capitan did you see an increase in memory utilisation? did you notice any CPU spikes after the 8GB upgrade? When I have tested the 8GB setup I saw heaps of CPU used by the "Kernel Task" somehow was like the Imac was never idleing.

I have tested the 8GB setup up to OSX 10.8.

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Hi,

I installed a Hynix DDR2 800mhz 2X4Gb ... The Mac reads it a 8gb installed. No Issues. I am doing a memtest and it access all the ram up to 7.98 GB which so far shows OK results and i am still waiting for the check to completely finish. The only thing is that when i open Youtube videos.. the imac slows down to the state of hanging. But it is a flash problem which i will address by following the procedures in other forums. It is a html5 problem and maybe can be corrected in due time. However, other apps run swiftly.

So i guess it is not an issue. Lets wait and see what the test says.

Shiva

Update (08/09/2015)

Hi Guys, Sorry for the late reply. I only got the email from this forum site today.

CONFIRMED that only 6GB of RAM works perfectly. 8 GB sends the system to an unknown abyss of darkness! LOL ...

@atroys - Hynix from Hong Kong

@bobhdeleon - Answered above

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What did the test say? Does it still work for you?

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Hi Shivaadm,

Thanks for the information on the RAM upgrade. Can you let me know where you purchased the RAM? I'm wary of pushing my 2008 iMac to 8gb, but I'm hoping to boost it to 6gb. Have you fixed the youtube problem yet?

Alex

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Hey Folks,

Just wanted to share my experience. Seen a lot of messages online saying that it works for other people. Just tried this on mine (Early 2008 20-inch, A1224), and it craps out with 8GB. (More specifically, it boots extremely slowly – on the order of 10 minutes – and I can't get past the login screen.)

FYI, the RAM I used was Komputerbay RAM purchased off Amazon, 800MHz unbuffered non-ecc per Apple's memory specification page.

6GB works fine.

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Did you update the systems firmware? Follow this Apple T/N: EFI and SMC firmware updates for Intel-based Macs. Give that a try.

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Take a good picture of the memory chips stampings so we can read the markings and post it here for us to see. Its also possible they sold you the wrong modules.

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Dan – Great thinking. Unfortunately, there's no firmware update for early 2008 imacs.

Here's the stick. I think I checked all the specs, but maybe you know more than I do?

http://imgur.com/IoYUqis

Here's Apple's memory spec page:

https://support.apple.com/en-us/HT201633

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Sorry, I can't seem to locate the memory chip spec sheet for these. The label implies the specs are correct. Try this take the older module out so only this newer unit is in (placed in the fist modules position. Does it work better? Also make sure you bottom out the module sometimes the module is not fully seated. If you are still having problems I would recommend you get a fresh module.

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Thanks for all your help Dan. I've got 6GB working fine already with one new module and one old module, and Komputerbay was kind enough to issue a partial refund, so I'm just gonna stick with what I've got so far.

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My Current Config:

SSD

6 GB of RAM

it runs smooth no problem.

if I move to 8GB, I get spikes of CPU all the times, and system that never idles.

I have tried different versions of OSX, 10.6, 10.7 and 10.8 the behaviour doesn't change

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What is the CPU's Clock rate? The higher speed systems hub controller has problems with 8 GB, Drop it down to 6 GB and double check your firmware here: About EFI and SMC firmware updates for Intel-based Mac computers

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Hi Gian Luca,

I'm curious to know if you're still having luck with 6gb of RAM several months later? Also, did it work "better" at 6gb than at 4gb? You wrote "no problems" but I'm wondering if the improvement was noticeable.

Alex

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Gian - as Dan stated, don't push it, you're looking for problems. If you need more speed it's better to go with a hard drive upgrade to a SSHD hybrid drive. BTW - Reflecting on your icon, I hope she dances better than she looks, she;s kind of doggy looking. https://www.youtube.com/watch?v=EVAdt5bH...

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Guys it's over 1,5 years that my system is running on 6 GB DDR2 and 512GB SSD (Sata 2) and so far I have noticed no issue at all.

I'm running 10.7 and I'm planning to move to 10.8.

I need the extra 2 GB of ram to run a windows VM for development purposes.

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Thanks, Gian.

This is promising news. I'm already running 10.9.5 (this is part of the reason my memory is being used up) due to an accidental update a year ago.

Do you recommend a seller for the 4GB RAM? From what I hear it's rather expensive.

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there is a legend around saying that Apple is pretty picky in choosing the hardware vendors.

the truth is that RAM has to comply with IEEE standards, so there is no actual difference between manufactures.

however I opened many Macs, and so far I have noticed that apple uses raftly those three manufactures:

Hynx (I have this one)

Micron

Samsung

Double check the speed, (mine is 800MHZ PC2-6400) and you should be fine .

Price should be around $60/$70 (Australian dollars)

however if you already install an SSD, the only upgrade left is going to 6GB of RAM.

Cheers

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Yes you can I just did it today. Machine runs great! Here is a link to the crucial ram I purchased on amazon. I almost want to upgrade to more lol but I'll probably get a new computer soon but then again my oldie but goodie still works great. Oh and I'm still on 10.6.8 Good luck!! https://www.amazon.com/Crucial-PC2-6400-...

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Please read above. Not all of this series will work with 8 GB! If you have a different series that is a different story.

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I have a A1224 2.66 core 2 duo with 2-4 GB makes 8 GB loads ever time runs good el Capitan . Duel boot with 18 Linux Mint shows 7. GB ram in system monitor.

Mike

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I have removed OS X from my 2008 iMac and installed Ubuntu a few days ago. I switched to a new Mac in 2015, and have had my old one in my basement for a few years, and last Friday I pulled it out and did some work on it. I’m planning on using it as a server computer to replace my previous server computer, which was either the first Intel iMac or the last PowerPC iMac, which used to be my brothers. Your answer talks about what Apple says it can do and what the developers for Apple said it can do, but what about Ubuntu? 4 GB is pretty bad for a server computer, and I can’t even use all of it. I have 3000 MB allocated to my server, and being able to upgrade that would be great. I have experienced connection timeouts while using it, and there are times where it can freeze and require a computer restart to get it working again. I connected it to Ethernet yesterday, so it should have a slightly better connection, but it’s still not great.

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Think of it this way a highway has three travel lanes and one breakdown for a total of four lanes. In some states during the morning rush the breakdown lane is allowed to have cars as the load of cars is to great. But, you really only have three lanes for the rest of the day,

In a way we are doing the same thing here. The RAM units come in fixed sizes 2, 4, 8, & 16. But, in some cases the address lines are limited to some other value. In our case 6 GB.

So you could use two modules 2 & 4 = 6 GB, or you could use 2 x 4 = 8 GB but these upper 2 GB are not accessible as the address lines to support them are disabled.

Now you might want to ask your self why are these upper lines not working! The CPU can access them but the platform logic can't! This gets into a problem Intel had with its platform chip set while it was intended to support 8 GB it turned out a problem was found just after the release and the upper lines were laser cut within the chip for the remainder of the run. Some early chips did sneak out with the lines active and these systems would crash as the memory addressing was not stable.

This has nothing to do with the OS it was a hardware design defect and at the time it was thought 6 was good enough!

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Frankly, I don't think iMac's make that great a server. Even the Mac mini is not very useful unless you upgrade it to SSD's and max out with two drives internally or use an external RAID drive set.

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