Overloading RAM on my iMac

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Level 1

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Overloading RAM on my iMac

Hello...

Please see here for reference. Apparently I am able to load two 2GB modules in my MacBook despite the original specs, which said 2GB total max.

So, can I do similarly on my '08 iMac, currently maxed out at 4GB? I.e., cram two 4GB modules into it? If it turns out the system can only address 6GB-7GB of that (as with the MacBook), that's OK. Turns out Mt. Lion is heavier lifting than this thing's used to. (I've considered a drive upgrade but that would require professional help. RAM I can do myself.)

Processor 2.8 GHz Intel Core 2 Duo

Memory 4 GB 800 MHz DDR2 SDRAM

On the other hand, I did some looking around and it would appear that DDR2 PC2-6400 is not available larger than 2GB. Would some other format do as well?

Thanx muchly,

Jeff

P.S., I eagerly await the next release of iMacs, whenever that might actually happen...😕

iMac (24-inch Early 2008), OS X Mountain Lion

Posted on Aug 28, 2012 2:26 PM

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Answer 1

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RRFS

Level 5

4,522 points

Aug 28, 2012 2:36 PM in response to Jeff Mark

go to Crucial or OWC they will recommend the proper amount of RAM for your system. I have 6GB in my one 2GB and one 4GB, works great. Be careful as Macs are very particular about their RAM, even some that meet specs won't work properly.

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Answer 2

MichelPM

Level 10

80,958 points

Aug 28, 2012 2:38 PM in response to Jeff Mark

The max RAM you can install into your iMac is 6 GBs.

No more than this.

Here's the specs for you RAM.

6.0 GB (Actual) 4.0 GB (Apple)

Memory Slots 2 - 200-pin PC2-6400 (800MHz) DDR2 SO-DIMM

You can buy reliable RAM online from Crucial memory or OWC.

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Answer 3

Jeff Mark Author

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Aug 28, 2012 2:38 PM in response to RRFS

Thanks. Please see my update tho. (I agree about Crucial, I recently bought a SSD for that MacBook and they were very helpful. But would they receommend spmething that excceeded mfr specs? But thanks for the suggestion.)

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Answer 4

RRFS

Level 5

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Aug 28, 2012 2:40 PM in response to Jeff Mark

No, because they want their guaranteed products to work properly. 😀

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Answer 5

MichelPM

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Aug 28, 2012 2:42 PM in response to Jeff Mark

No.

Your iMac is not capable of addressing more RAM than the 6 GB limit.

Sorry.

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Answer 6

Jeff Mark Author

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Aug 28, 2012 2:58 PM in response to MichelPM

Hi Michel,

I'm missing something in your response, please let me try again. If I could put 8GB into my iMac but only access 6GB, that would be OK. That's similar to the situation with my MacBook.

I have two slots. Currently they both contain a 2GB DIMM. If I understand what you and RRFS are telling me, if I could get 8GB (say, two 4GB DIMMs) into it, I could address about 6GB of that, which, as I said would be an improvement.

The issue would seem to be finding actual 200-pin PC2-6400 (800MHz) DDR2 SO-DIMM in a 4GB size. Crucial didn't seem to carry any, but OWC has a 6GB kit (!). Little pricey, tho. Also, I thought iMac RAM had to be in matched paiurs. Maybe not.

Thanks, have some points.

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Answer 7

RRFS

Level 5

4,522 points

Aug 28, 2012 3:02 PM in response to Jeff Mark

When I got my 6GB of RAM I tried putting the 4GB module in the fist slot, it was not recognized, so that would be a no to the 8GB question.

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Answer 8

Jeff Mark Author

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Aug 28, 2012 3:11 PM in response to RRFS

You might have an opportunity ro teach me something here. As I said above, I was under the impression that RAM had to be installed in pairs. I guess not. So, are you and Michel telling me that I could replace one of my 2GB modules with a 4GB module (as apparently available from OWC), and get to use all 6GB, but it has to go in the #2 slot?😕

Is that right? How bizarre. Was it just not there in #1 (i.e., "0GB"), or did the system refuse to start? Do you understand what that was about, and can you explain it briefly in terms understandable by one such as myself?

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Answer 9

RRFS

Level 5

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Aug 28, 2012 3:15 PM in response to Jeff Mark

It gave me 3 beeps and refused to start. I'm not sure if the "pair" of modules I got from Crucial is matched somehow or maybe it's tested by them to know it works together. I only know it was at least the same specs just 4GB instead of 2GB.

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Answer 10

Jeff Mark Author

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Aug 28, 2012 3:19 PM in response to RRFS

But it was OK when you put the 4GB in #2? And the system saw all 6GB?

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Answer 11

MichelPM

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Aug 28, 2012 3:33 PM in response to Jeff Mark

Yes, when applicable, it's always better to install RAM into an iMac in pairs.

But for the iMsc models that take the 6 GBs of RAM, putting (2) 4 GB RAM pairs does not work in these Macs.

I believe it's OWC that tests how much max RAM can be installed in Macs.

Not all Mac models can exceed Apple's stated max. RAM amounts.

Those that do exceed Apple's stated amount can vary widely in their amount of max. RAM.

For the 2008 models the only combination that was found to work is to install a 2 GB, than a 4 GB stick into these Macs for a total of 6 GBs.

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Answer 12

MichelPM

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Aug 28, 2012 3:35 PM in response to Jeff Mark

Yes, That would be the correct order for the RAM.

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Answer 13

Jeff Mark Author

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Aug 28, 2012 3:54 PM in response to MichelPM

Let me complicate this just a bit more.

My iMac has one 2GB PC2-6400 DDR2 800MHz SO-DIMM 200 Pin that I will be removing. My MacBook takes PC2-5300 DDR2 667MHz SO-DIMM 200 Pin.

Would the former be likely to work in my MacBook (meaning one fewer PC2-5300 DDR2 667MHz — or PC2-6400 DDR2 800M, maybe — that I have to buy)?

In fact, let's say I got one of OWC's 6GB kits for the iMac, could I just move those into the MacBook? That would save a few $$.

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Answer 14

RRFS

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Aug 28, 2012 3:54 PM in response to Jeff Mark

Doubt it would work. I wouldn't take the chance of it damaging some other component like the motherboard if it has a different pin configuration (for some inexplicable reason).

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Answer 15

MichelPM

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Aug 28, 2012 4:07 PM in response to RRFS

As was stated previously, Macs are highly picky about RAM.

Laptop and desktop RAM are different and different specs.

There is no mixing of RAM types, either.

If the RAM is not of the proper specs for the Mac, in question, it wil not work and/possibly do other damage, as well.

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