More than 4GB RAM in latest iMac 3.06 ?

The norm. is that the iMacs motherboard will only address the memorary that apple states.

For example my white imac 24" & the limit is set to3GB, your's is 4GB.

This is set on the hardware someone... but basically it will only be able to use 4GB so putting in any more is a waste.

The maximum amount of RAM is dictated by the hardware and the computer is physically incapable of using more than 4GB. if you put in 8, it shows up as 4 and can only use 4, so you'd be wasting your money.

There aren't any 4gb SoDimms on the market, so you couldn't if you wanted. When/If they are available it may be possible.

The iMac just like the Macbook Pro and current Macbook can address upto and including 8GB of DDR2 sodimm ram, unfortunately 4GB module are rare and very expensive.

Memory limitations are set by the chipset not by Apple, the current chipset supports upto 8GB or ram.

http://www.gbmicro.com/product.htm?...ory&Category=8GB SODIMM DDR2-667 DUAL CHANNEL

you need to call for a price

http://shop.kingston.com/partsinfo.asp?promo=PRCGRBR&ktcpartno=KVR667D2S5K2/8G

$900 or £450 ish

uk price is £500 from
http://www.morecomputers.co.uk/extra.asp?pn=KVR667D2S5K2/8G

from http://www.apple.com/imac/specs/

Processor and memory

* 2.4GHz, 2.66GHz, 2.8GHz, or 3.06GHz Intel Core 2 Duo processor
* 6MB shared L2 cache at full processor speed
* 1066MHz frontside bus
* 1GB (one 1GB SO-DIMM) or 2GB (two 1GB SO-DIMMs) of 800MHz DDR2 SDRAM; two SO-DIMM slots support up to 4GB

Click to expand...

(This is for the latest generation iMac.)

So whilst you CAN add more than 4GB or RAM the iMac itself is only capable of addressing upto 4GB.

I don't know whay they do this, but they do.

bentoms said:

So whilst you CAN add more than 4GB or RAM the iMac itself is only capable of addressing upto 4GB.

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Unless Apple has firmware-disabled the memory controller of the Santa Rosa chipset, the iMacs (and MacBooks and MacBook Pros) should be able to take 8 gb of RAM. Until someone actually puts in two 4-gig sticks, we won't know for sure.

Cave Man said:

Unless Apple has firmware-disabled the memory controller of the Santa Rosa chipset, the iMacs (and MacBooks and MacBook Pros) should be able to take 8 gb of RAM. Until someone actually puts in two 4-gig sticks, we won't know for sure.

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And if the iMacs could use 4GB, why do you think Apple would be keeping it a secret?

mreg376 said:

And if the iMacs could use 4GB, why do you think Apple would be keeping it a secret?

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The original Mac Pro can take 32GB (and perhaps more, but there aren't 8GB FB-DIMMs), but Apple never marketed over 16GB.

It has to do with availability. The only 4GB FB-DIMMs at the time were prohibitively expensive. Apple isn't going to try to sell you an upgrade that costs more than your computer.

mreg376 said:

And if the iMacs could use 4GB, why do you think Apple would be keeping it a secret?

Click to expand...

They did with the second gen Intel MacBooks, MacBook Pros and Minis. Do you remember that?

Cave Man said:

Unless Apple has firmware-disabled the memory controller of the Santa Rosa chipset, the iMacs (and MacBooks and MacBook Pros) should be able to take 8 gb of RAM. Until someone actually puts in two 4-gig sticks, we won't know for sure.

Click to expand...

I don't think it's to do with the firmware, i think it's to do with the logic boards that they use.

bentoms said:

I don't think it's to do with the firmware, i think it's to do with the logic boards that they use.

Click to expand...

See this document on the Santa Rosa chipset from Intel. Page 2, second column.

Apple has firmware-restricted its computers in the past. For example, both the first gen Intel Mac Mini and current Mac Mini are based on the same chipset (Calistoga). The only difference between them is the former shipped with Core Solo/Core Duo, while the latter uses Core 2 Duo. Both chips can address >3 gb of RAM, but the the CS/CD controller was EFI (firmware) restricted to two 1 gig SO-DIMMs. If you put more than a 1 gig SO-DIMM in either slot, the computer will not even boot.

The current Minis do not have this restriction. You can put 1/2 gig chips (i.e., 3 gigs) or 2/2 gig chips (i.e., 4 gigs) in its two SO-DIMM slots. Either way, you have access to 3 gigs (or 3.1 gigs with 2/2 gig) because the chipset can only access that much (32 bit). (Edit: Even Apple's web site lists only 2 gigs as the limit for the Mini, which is clearly not the case.) The Santa Rosa is 64 bit, thus can address 8 gigs with its memory controller (according to Intel). The cpu has nothing to do with it because you can put a C2D chip into a first-gen Intel Mini and you still are restricted to 2 gigs max.

Tallest Skil said:

The original Mac Pro can take 32GB (and perhaps more, but there aren't 8GB FB-DIMMs), but Apple never marketed over 16GB.

It has to do with availability. The only 4GB FB-DIMMs at the time were prohibitively expensive. Apple isn't going to try to sell you an upgrade that costs more than your computer.

Click to expand...

Well, I don't think Apple would be required to try to sell you an expensive upgrade just because they tell you that as a feature the iMac supports up to 8GB for "future" expansion. If it's true that iMacs can use 8GB, which I am not yet convinced is even true, I think a better reason that Apple would not mention it is to maintain the divide between the iMac and the Mac Pro. Of course if Apple feels strongly about that, why not just firmware-limit the iMacs in the first place? I think that's more likely than a "secret" feature.

fredsarran said:

Physically, I can buy expensive 2 chips of 4GB and insert them in the iMac 3.06 - But then, would they actually work ? Would the system profiler show the full 8GB ?

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If your iMac would boot, System Profiler would report 8 gb or RAM. However, SP only reports what the hardware is, not what it's doing. To determine if you really have 8 gb RAM, you'd have to open Activity Monitor, click on System Memory and sum the Free and Used values.

Anybody tried ?

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As far as I know, you'd be the first. Make sure you let us know how it goes.

Would it work without any sort of hacking some hardware or files ? or with ?

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Shouldn't require hacking. If it does, it's in the firmware and you'd have virtually no chance of modding it.

What the name of the chip/motherboard in the iMac 3.06 ? Santa Rosa ? or... ?

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The iMacs, MacBooks and MacBook Pros all ship with Santa Rosa now, with Penryn cpus.

feelthefire said:

The maximum amount of RAM is dictated by the hardware and the computer is physically incapable of using more than 4GB. if you put in 8, it shows up as 4 and can only use 4, so you'd be wasting your money.

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There are some cases where the Mac can take in more RAM than specs, once higher capacity RAM becomes available.

Case in point, spec of certain Mac Minis lists max ram of 2gb, but they can actually take 3gb.

So time might change things (except for pre-santa rosa of which the limit is 3gb).

fredsarran said:

So, the conclusion would be : Do not upgrade to more than 4GB of RAM - Too expensive, not supported by Apple and might damage the iMac.

Anybody with a better conclusion ? It is a pity to think that maybe I could upgrade to 8GB and that allows a real speed boost. I guess we have to believe and trust Apple on that one.

Also it is a too expensive risk.'

Cheers.

Click to expand...

For £500/$900 you can load up your iMac or any other santa rosa chipset based Mac or PC with 8 GB of ram if you please. There is no technical limitation imposed. The only limitation is that the marketing department can't sell you 8 GB of ram just now because no one would buy it.

Unfortunately i can only testify to the Macbook Pro however there architecture is the same at the chipset level.

fredsarran said:

So, the conclusion would be : Do not upgrade to more than 4GB of RAM - Too expensive, not supported by Apple and might damage the iMac.

Anybody with a better conclusion ? It is a pity to think that maybe I could upgrade to 8GB and that allows a real speed boost. I guess we have to believe and trust Apple on that one.

Also it is a too expensive risk.'

Cheers.

Click to expand...

how would putting >4GB of RAM damage your mac? you could always remove the DIMMs

fredsarran said:

...

Click to expand...

In the other thread your were debating between Mac Pro and iMac. It was probably more sense to get a Mac Pro instead if you really need that much memory.

Putting more than 4 GB in the iMac will not damage the computer in any way, just make sure it meets the specs.

bentoms said:

from http://www.apple.com/imac/specs/

(This is for the latest generation iMac.)

So whilst you CAN add more than 4GB or RAM the iMac itself is only capable of addressing upto 4GB.

I don't know whay they do this, but they do.

Click to expand...

Apple is pretty notorious for understating the max amount of ram their computers can use. I had 3GB in my macbook (and do in my work computer - a macbook) for a year with no ill effects, despite apple's statement that the computer couldn't handle more than 2GB.

I wish
I read an article about Snow Leopard being able to access 16TB of RAM - holy cow