I have an iMac 27" mid 2010 with Intel i7 2.93Ghz and MacOS 10.9. For now it have 8GB stock 4x2GB RAM but I want install at least 16GB+ RAM.

All official documents and data-sheets (especially Intel's chipset data-sheet) tells me that I can't install more than 16GB RAM with 4x4GB plates. But experience of all other users tell me that I can successfully install up to 32GB RAM with help of 8GB plates. Who is right?

I want to install 2x8GB of this Kingston: KVR1333D3S9/8G with 2x2GB of stock memory and get 20GB in total (smth like this this).

So, will it fit and work?

2 Answers 2


Here is your model on EveryMac.com, according to them it will support a maximum of 32 GB of system RAM.

The mid-2010 iMacs support 1333 MHz PC3-10600 DDR3 SO-DIMMs with 204-pin. Crucial mirrors this statement.

According to the datasheet you linked, the Kingston RAM is 667MHz. I believe when it comes to RAM, the machine simply lowers the frequency to a consistent level in order for the RAM to be compatible across the entire computer.

  • "According to the datasheet you linked, the Kingston RAM is 667MHz" - wow, thank you, Patrick! I didn't noticed that, so it could impact to performance of my system completely because all RAM would work on 667MHz instead of 1333MHz. "Crucial mirrors this statement" - you linked 4GBx2=8GB kit when I need 8GBx2 which Crucial supplies as PC3-12800, not PC3-10600. Not so important but it will add some disbalance in my configuration. If we exclude Kingston because of low frequency, only available RAM for me is [this](corsair.com/en-gb/…
    – Venique
    Commented Jan 30, 2015 at 22:45

Unofficially, your iMac supports up to 32GB (4x8GB) so yes you should be fine. Apple (and others) generally quote memory specs with reference to memory types available at the time of design. This MacBook I'm using now (Early 2011 i7) is specced for 8GB maximum RAM even though it's currently running 16GB without issue.

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