Q: IMac RAM: 16 or @20 GB?

Apple only supports officially 16 GB of memory on your iMac, but you can install 32 GB of memory (4x8 GB of memory) on your iMac. You can buy the RAM in OWC or Crucial to guarantee the maximum compatibility > http://eshop.macsales.com/shop/memory/iMac/2011/DDR3_21.5_27

If you need help installing RAM > http://support.apple.com/kb/HT1423?viewlocale=en_US#1

Your model can handle up to 32 GBs of RAM. Visit

OWC where you may purchase memory kits for your computer and find tutorials on how to install/replace RAM. You can do what the dealer has told you.

You can install two 4 GB modules for 12 GB or two 8 GB modules for 20 GBs or four 4 GB modules for 16 GBs or four 8 GB modules for 32 GBs. But you need not install and more RAM than you think you will ever need.

I have a model MC309LL/A with i5, 2 5 MHz quad, with 2x4gb and am going to add 2x8gb to the open slots.  Does anyone know if that installation is ok?

Thanks Jim

Yes, it's OK.

Thanks, Kappy

You are welcome