Mid 2011 iMac memory

A friend just picked up a used mid 2011 iMac with 21" monitor. I happen to have a 27" mid 2011 model and so I am the go-to friend with questions. His iMac has 4 GB of memory (2 x 2 GB) and he wants to upgrade to 8 GB using a single SO-DIMM he has already. Not wanting to give him incorrect info, can he use a single SO-DIMM? I am thinking he has to use either 2 or 4 of the same size.

Your friend's 2011 iMac should have 4 ram slots. I also believe that it is no longer necessary to install ram in matching pairs. Thus your friend's iMac should have 2 ram slots free...thus any density ram (1gig, 2gig, 4gig, or 8gig) can be installed into those two vacant slots.

Regarding the 8gig stick of ram. Yes an 8gig stick of ram can be installed...but not just ANY 8gig stick of ram can be in there. It must be the correct ram (1333 MHz PC3-10600 DDR3 SO-DIMMs (204-pin)).

So assuming the 8gig stick of ram is compatible...your friend would have 2 + 2 + 8 = 12gig of ram total. One ram slot free.

- Nick

p.s. Mid-2011 iMac's have a max. ram capacity of 32gig (4 x 8gig).

Thanks, pigoo3. The 8 GB ram is the correct item. I've always thought only matching SO-DIMM could be used in an even number of slots. I know he will be pleased to know he can now use all his RAM for a total of 12 GB
I wish I had known that for my system. I added two 8 GBs to mine in place of the two 2GB it came with and unfortunately, I no longer have them

tape said:

Thanks, pigoo3. The 8 GB ram is the correct item. I've always thought only matching SO-DIMM could be used in an even number of slots. I know he will be pleased to know he can now use all his RAM for a total of 12 GB.

Click to expand...

Matching sticks of ram used to be required on many older models. But with newer Mac's I do not believe it is still mandatory. There also used to be a small performance benefit if matched ram was installed...but I'm not 100% sure if that is a benefit any longer as well (at least as it applies to mid-2011 iMac's).

tape said:

I wish I had known that for my system. I added two 8 GBs to mine in place of the two 2GB it came with and unfortunately, I no longer have them

Click to expand...

Sorry to hear that. Yes...you would have had a total of 20 gig. But I bet that 16gig is running just fine!

- Nick