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GGJstudios

macrumors Westmere
May 16, 2008
44,509
911
Is the maximum RAM limit hardware or software based? Is there no way to change it? Thanks.
Hardware. You can find specs on all Apple products, including maximum RAM:
 

Adomian

macrumors newbie
Apr 9, 2012
18
0
127.0.0.1
It is limited by the hardware. Each Mac has a bay of RAM chips, a basic 4GB model will have two 2GB chips. A modern iMac will have four available slots (two already filled). You can buy RAM in sizes up to 16GB, I believe, meaning that 4 slots can have 64GB of RAM, which would mean replacing your original 4GB. You can also add RAM chips to the two empty slots for up to 36GB.

**Sorry, this is completely wrong!
It IS limited by hardware but the numbers are wrong. An iMac can have up to 32GB.
 
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ri0ku

macrumors 6502a
Mar 11, 2009
952
0
It is limited by the hardware. Each Mac has a bay of RAM chips, a basic 4GB model will have two 2GB chips. A modern iMac will have four available slots (two already filled). You can buy RAM in sizes up to 16GB, I believe, meaning that 4 slots can have 64GB of RAM, which would mean replacing your original 4GB. You can also add RAM chips to the two empty slots for up to 36GB.

The iMac doesn't support ram over 16GB, its not read or usable. The hardware limits it. Not all motherboards/logic boards can support huge amounts of ram like that.
 
Nov 28, 2010
22,670
28
located
It is limited by the hardware. Each Mac has a bay of RAM chips, a basic 4GB model will have two 2GB chips. A modern iMac will have four available slots (two already filled). You can buy RAM in sizes up to 16GB, I believe, meaning that 4 slots can have 64GB of RAM, which would mean replacing your original 4GB. You can also add RAM chips to the two empty slots for up to 36GB.
The iMac doesn't support ram over 16GB, its not read or usable. The hardware limits it. Not all motherboards/logic boards can support huge amounts of ram like that.


The 2011 iMac can support up to 32 GB RAM with four 8 GB of 204-pin DDR3 SO-DIMM RAM modules, the current maximum in that size.
Since the OP did not specify, what exact iMac s/he is talking about, and the signature mentions a 2006 iMac, we can't really help.
Mister GGJstudios though gave the OP the means to let the OP help him or herself.
 

ri0ku

macrumors 6502a
Mar 11, 2009
952
0
That's not true. Many iMac models support up to 32GB. Read the links posted to get the facts.

His 2006 iMac in his sig does not though..

Edit: The 2006 iMac supports up to 4GB of ram, I thought they supported 16GB then hmm. Which iMac only support 16GB was it 2010 ?
 

GGJstudios

macrumors Westmere
May 16, 2008
44,509
911
His 2006 iMac in his sig does not though..
No, but since the OP didn't specify which iMac they were inquiring about, the links will enable them to find the facts for whichever model they want.
Which iMac only support 16GB was it 2010 ?
Some of the 2010 models support a max of 16GB, some 32GB. The EveryMac.com links will show which.
 

ri0ku

macrumors 6502a
Mar 11, 2009
952
0
Look at the EveryMac link GGJstudios provided.

Yes but theres many different models some showing 32 some showing 16 so I wasn't sure if the information was right. Seems that just a variety of the 2010 models had different maximum ram.

----------

No, but since the OP didn't specify which iMac they were inquiring about, the links will enable them to find the facts for whichever model they want.

Some of the 2010 models support a max of 16GB, some 32GB. The EveryMac.com links will show which.

Yeah thanks I found that while looking, wasn't sure if it was a mistake or not didn't think they would have different max amounts on the same year model.
 

GGJstudios

macrumors Westmere
May 16, 2008
44,509
911
Yeah thanks I found that while looking, wasn't sure if it was a mistake or not didn't think they would have different max amounts on the same year model.
In 2010, only the 27" supported 32GB, while the 21.5" maxed at 16. The next year, they both supported 32.
 

ri0ku

macrumors 6502a
Mar 11, 2009
952
0
In 2010, only the 27" supported 32GB, while the 21.5" maxed at 16. The next year, they both supported 32.

ah, well I recently bought a 21.5 iMac from the higher ed store, (2011 model) they told me that the iMac only would read 16GB of ram (when I asked them about voiding warranty etc on replacing ram and the hdd)

So I wonder if they got mixed up and were thinking about the 2010 model.
 

GGJstudios

macrumors Westmere
May 16, 2008
44,509
911
So I wonder if they got mixed up and were thinking about the 2010 model.
Quite possible, but more likely is the fact that Apple has routinely claimed a lower max RAM than models are capable of using.
 

acehlis

macrumors newbie
Jul 29, 2011
3
1
Not Just H/W ... Software Too

Other World Computing sells after market Memory upgrades for MacPro. Apple says max 64GB, but OWC sells a 128GB upgrade kit. There is one caveat though, you must boot into Windows via Bootcamp because Mac OS X will only recognize 96GB of RAM. I've been trying to find more info on why that limit exists if OSX is a 64-bit OS.
 
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mac-collector

macrumors regular
Original poster
Apr 8, 2012
117
0
Europe
Thanks for all the good, honest answers. I wasn't really asking what my iMac could use, just whether the limit was software or hardware based, which has been answered very well.

Thank-you.
 

martyr

macrumors member
Jun 19, 2007
34
12
Not Just H/W ... Software Too

Other World Computing sells after market Memory upgrades for MacPro. Apple says max 64GB, but OWC sells a 128GB upgrade kit. There is one caveat though, you must boot into Windows via Bootcamp because Mac OS X will only recognize 96GB of RAM. I've been trying to find more info on why that limit exists if OSX is a 64-bit OS.

You're correct. I wonder if High Sierra (10.13) or Mojave (10.14) has increased this software limitation?
 

nambuccaheadsau

macrumors 68020
Oct 19, 2007
2,024
510
Blue Mountains NSW Australia
On older Macs the limit was imposed by what memory modules were manufactured at that time,

For example, the 2011 27" iMc as quoted above on release took a maximum of 4 x 4GB modules, total 16GB. After release of 8GB modules, which worked in that model, this then became 32GB.
 
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