Extra Ram for an iMac

Hi all, I hope someone can point me in the right direction.
I need extra Ram for my iMac, it's a Retina, 5K, 27", late 2015 model.
At the moment I have the 8GB of Ram in 2 of the slots (4GB in each ) and 2 empty slots.
Do I need buy 2 more, as opposed to just filling one slot, do they need be the same size as the ones already installed or can I go bigger ?
I did call the Apple store where I purchased the computer but the guy I spoke to was less than helpful tbh and they didn't sell it anyway !!
Computer tells me the ones installed are SO-DIMM, PC3-12800, unbuffered, non parity, 204 pin, 1600MHz, DDR3, SDRAM.
Any help would be great.
Thankyou.
Janet
I need extra Ram for my iMac, it's a Retina, 5K, 27", late 2015 model.
At the moment I have the 8GB of Ram in 2 of the slots (4GB in each ) and 2 empty slots.
Do I need buy 2 more, as opposed to just filling one slot, do they need be the same size as the ones already installed or can I go bigger ?
I did call the Apple store where I purchased the computer but the guy I spoke to was less than helpful tbh and they didn't sell it anyway !!
Computer tells me the ones installed are SO-DIMM, PC3-12800, unbuffered, non parity, 204 pin, 1600MHz, DDR3, SDRAM.
Any help would be great.
Thankyou.
Janet

You can go to Crucial's website and have it scan your computer, it'll then advise (and sell you) the right memory for it
Or you can put in your make/model etc.
www.crucial.com/uk

Or you can put in your make/model etc.
www.crucial.com/uk

If I recall correctly the RAM needs to be installed in pairs. So you'll need 2 not one. I also believe that they need to be matched - so you can have 2 4GB and 2 8GB but not three 4's and 1 8GB - I hope that makes sense.
It might be worth looking in the utilities folder to check if you actually need a RAM upgrade. There is an app in their that monitors memory usage. After upgrading to my Canon 5DS I found that the issue was less my RAM and more the HDD - what was needed was a solid state drive - you don't mention if you have a fusion drive/ SDD or standard HDD. Here is where buying an integrated device becomes problematic as upgrading to a SSD is a specialist job. In the end I found it more cost effective to sell the Mac and upgrade to a model with a fusion drive.
It might be worth looking in the utilities folder to check if you actually need a RAM upgrade. There is an app in their that monitors memory usage. After upgrading to my Canon 5DS I found that the issue was less my RAM and more the HDD - what was needed was a solid state drive - you don't mention if you have a fusion drive/ SDD or standard HDD. Here is where buying an integrated device becomes problematic as upgrading to a SSD is a specialist job. In the end I found it more cost effective to sell the Mac and upgrade to a model with a fusion drive.

Quote:check if you actually need a RAM upgrade
What would you check ?
A quick check in creating a mask on an adjustment layer I get similar figures to chase Physical 8GB and used 5.6GB ( varies slightly )


You need 4 X 4GB for 16 GB RAM. So another two exactly the same as you have, - but dont buy from Apple. Or replace the two 4 GB with two 8 GB for 16, - willl allow an easy expansion to 32 GB by adding another 2 x 8GB later.
Theyre 1600 Mhz DDR3, and as long as the new pair are matched with each other you should have no problems. These memory sticks are readily available at any computer supply store.
You can never have too much RAM!
Theyre 1600 Mhz DDR3, and as long as the new pair are matched with each other you should have no problems. These memory sticks are readily available at any computer supply store.
You can never have too much RAM!