Memory Upgrade 4 to 16GB

[BarkingGhost]

Mid-late 2011 27" iMac with Core i7 processor. Has four banks, but only two are occupied (2x2GB). Maximum memory allowed is 16GB.

Can I use 2x8GB modules (using only two banks), or must I 4x4GB (using four banks)? I am not planning on re-using the factory installed memory.

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Never mind. This Apple link suggests all four banks need to be occupied as it does not allow for 8GB modules.

 

[jdblas69]

I think Apple states max ram 16gb, but I am pretty sure you can run 32gb in this model.

You can just run 2 banks at 8gb each.

 

[firedept]

Mid-late 2011 27" iMac with Core i7 processor. Has four banks, but only two are occupied (2x2GB). Maximum memory allowed is 16GB.

Can I use 2x8GB modules (using only two banks), or must I 4x4GB (using four banks)? I am not planning on re-using the factory installed memory.

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Never mind. This Apple link suggests all four banks need to be occupied as it does not allow for 8GB modules.

Maximum allowed for your machine is 32GB. You can add 2 x 8GB and leave the original in for a total of 20GB. Many people have gone this route. There is no need to remove original 4GB.

I have done this with my current late 2012 iMac. Came with 8GB, added 16GB, for 24GB total. Have not had any issues. Just make sure you get proper RAM. OWC & Crucial are 2 good places to get it.

 

[rkaufmann87]

Mid-late 2011 27" iMac with Core i7 processor. Has four banks, but only two are occupied (2x2GB). Maximum memory allowed is 16GB.

Can I use 2x8GB modules (using only two banks), or must I 4x4GB (using four banks)? I am not planning on re-using the factory installed memory.

----------

Never mind. This Apple link suggests all four banks need to be occupied as it does not allow for 8GB modules.

As has already been mentioned your late 2011 iMac can handle up to 32GB (4x8GB DIMMs). On my late 2011, it came with 8GB and I added an additional 16GB (2x8GB) to get 24GB. It has been running like that for almost a year. Depending on where on the planet you are located I'd recommend buying from either www.macsales.com or Crucial if you are in North America, anywhere else I'd recommend just Crucial.

Stay away from cheap RAM like "Value Ram", iMacs can be finicky when it comes to RAM. Also if you are a little nervous doign the upgrade it's very simple, www.macsales.com have video tutorials that will illustrate how it's done.

 

[Bear]

Mid-late 2011 27" iMac with Core i7 processor. Has four banks, but only two are occupied (2x2GB). Maximum memory allowed is 16GB.

Can I use 2x8GB modules (using only two banks), or must I 4x4GB (using four banks)? I am not planning on re-using the factory installed memory.
...

Actually your Mac does support 8GB memory modules.

Might I suggest you leave the original memory in and add 2x8GB into the empty slots to give you a total of 20GB of RAM?

 

[magilla]

Actually your Mac does support 8GB memory modules.

Might I suggest you leave the original memory in and add 2x8GB into the empty slots to give you a total of 20GB of RAM?

Since you seem to know, how can I find out how much MY late 2011 i3 iMac (3.2GHz) will ultimately support? Currently has 8GB (2x4) installed in 2 slots.

 

[Bear]

Since you seem to know, how can I find out how much MY late 2011 i3 iMac (3.2GHz) will ultimately support? Currently has 8GB (2x4) installed in 2 slots.

If it's an i3 3.2GHZ, it's a Mid 2010 model and can support 16GB.

See EveryMac.com to find out the official capacities as stated by Apple and also what the actual maximum memory capacity is as tested by various sources.

 

[BarkingGhost]

As has already been mentioned your late 2011 iMac can handle up to 32GB (4x8GB DIMMs). On my late 2011, it came with 8GB and I added an additional 16GB (2x8GB) to get 24GB. It has been running like that for almost a year. Depending on where on the planet you are located I'd recommend buying from either www.macsales.com or Crucial if you are in North America, anywhere else I'd recommend just Crucial.

Stay away from cheap RAM like "Value Ram", iMacs can be finicky when it comes to RAM. Also if you are a little nervous doign the upgrade it's very simple, www.macsales.com have video tutorials that will illustrate how it's done.

Are you suggesting the Apple documentation is incorrect when it says the maximum is 16GB for the mid-late 2011 model 27" iMac? Proverbial copy & paste:

Applicable models

iMac (27-inch, Mid 2011)
iMac (21.5-inch, Mid 2011)
iMac (27-inch, Mid 2010)
iMac (21.5-inch, Mid 2010)
iMac (27-inch, Late 2009)
iMac (21.5-inch, Late 2009)
Memory specifications

These iMac models have these memory specifications:
Number of memory slots 4
Base memory 4 GB (but is configured to order)
Maximum memory 16 GB
Note: For the iMac (Late 2009) models, you can use 2 GB or 4 GB RAM SO-DIMMs of 1066 MHz DDR3 SDRAM in each slot. For the iMac (Mid 2010) and iMac (Mid 2011) models, use 2 GB or 4 GB RAM SO-DIMMs of 1333 MHz DDR3 SDRAM in each slot.

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Actually your Mac does support 8GB memory modules.

Might I suggest you leave the original memory in and add 2x8GB into the empty slots to give you a total of 20GB of RAM?

I'm not against buying 8GB modules and adding them to what is already in there, but when I read the Apple documentation for my model year iMac it says the maximum is 16GB. If this is incorrect so be it. Heck, I suppose I could buy the 16GB upgrade kit (2x8GB) add them, see if the iMac boots, and if not remove the 2x2GB modules and relocate the 8GB modules. Worse case is I return the memory to the local store and buy the 4GB module kits.

 

[jdblas69]

The official statement from Apple regarding RAM is usually less than what they can actually support for many macs, whether it be imac, MBP's, etc.

www.everymac.com is a good website that will usually state if third parties have installed and have determined that in most cases they can support more ram or certain module sizes.

 

[BarkingGhost]

The official statement from Apple regarding RAM is usually less than what they can actually support for many macs, whether it be imac, MBP's, etc.

www.everymac.com is a good website that will usually state if third parties have installed and have determined that in most cases they can support more ram or certain module sizes.

Thank you for that link! Here is does say the same thing that several of you have stated. Many thanks all. I'll buy the 16GB upgrade kit and see how it goes.

Heck, if it goes well I may be tempted to buy a second 16GB kit and max out the memory.

 

[MrGimper]

I did the same for my early 2011 cMBP.

The max RAM as specified by apple was 8GB, but people realised it could actually take 16GB.

I think it was because at time of manufacture you could only get 4GB SODIMMs, rather than a technical limit.

 

[RedReplicant]

Well, I have 2x2GB and 2x8GB working fine in mine.

 

[BarkingGhost]

All, thank you for the information. Yesterday I installed the additional 16GB along side the existing 4MB. Booted without any issues. Many thanks for the insight.