Adding memory to a 27" iMac

[MikeFromMesa]

After doing some research and posting some questions on this forum I have pretty much decided that my next Mac will be an iMac. Thank you to those who were kind enough to respond to my earlier postings about the Mini.

The base 27" Retina iMac comes with 8GB of memory in 2 4GB sticks, but with 4 slots. I thought I would upgrade the memory to 16GB or 24GB by adding memory from either Crucial or OWC and add either 2 4GB sticks, 1 8GB stick or 2 8GB sticks, depending on what seemed like the best way to proceed and what the iMac hardware restrictions allowed, so I called Crucial (and then OWC) to try to get answers to the following questions:

1) Can memory sizes be mixed?
2) Can I add a single memory stick? Or do they have to be added in pairs?
3) Can I mix memory from different manufacturers?

Unfortunately I got completely different answers from the Chat lines at Crucial and OWC. Can memory sizes be mixed? Yes from one, it is a bad idea from the other. Can I add a single memory stick? Yes from one, no from the other. Can I mix memory from different manufacturers? Yes from one, it is a bad idea from another. I have bought upgrade memory from Crucial many times and always been happy with the memory. It has always worked and I trust them to supply good equipment but I don't know whether or not their advice might be influenced by the desire to sell more memory.

Given that, I thought the best way to get answers to these questions was to ask people who had an iMac and might have already added memory (as I assume many 27" iMac purchasers would have already done). Can anyone answer the questions I listed above?

 

[dtravis7]

I will answer this the clearest I can.

If you put in one stick it will not be running in Dual Channel and that will give you a hit in Memory performance. On some benchmarks here I saw as much as 15-20% on some tests. Same with different sizes in each bank. You already have 2 matched sticks in the first bank, I would suggest 2 more that match in the 2nd bank. You can put 2x8GB in the 2nd bank and it will still be fine, but a 4 and an 8 would not be Dual channel.

Also I find it best to go with matching Ram modules in each bank. So 2 OWC or 2 Crucial if you get what I am saying.

With a machine like that, it's best to go all the way and not cut corners!

Hope this helps.

 

[MikeFromMesa]

I will answer this the clearest I can.

If you put in one stick it will not be running in Dual Channel and that will give you a hit in Memory performance. On some benchmarks here I saw as much as 15-20% on some tests. Same with different sizes in each bank. You already have 2 matched sticks in the first bank, I would suggest 2 more that match in the 2nd bank. You can put 2x8GB in the 2nd bank and it will still be fine, but a 4 and an 8 would not be Dual channel.

Also I find it best to go with matching Ram modules in each bank. So 2 OWC or 2 Crucial if you get what I am saying.

With a machine like that, it's best to go all the way and not cut corners!

Hope this helps.

Yes, it does. In fact it addresses all of my questions and probably addresses why I got different answers from the people I chatted with. Perhaps that is what they were referring to when they said "it is not a good idea".

Thank you for your clarity.

 

[pigoo3]

After doing some research and posting some questions on this forum I have pretty much decided that my next Mac will be an iMac.

Congrats Mike on narrowing things down to an iMac.

- Nick

 

[MikeFromMesa]

Congrats Mike on narrowing things down to an iMac.

Thanks. This should have been easy but it turned out to be a really difficult choice for me.

I have been going back and forth between the Mini (max configuration), the 27" iMac (4.0 GHz i7) and the Pro (base version). The Mini was appealing because it was half the price of the others, the Pro was appealing because, well, it is a Pro, and the iMac was least appealing because I already have a monitor that suits me well.

In the end I decided on Door Number 3 because I realized that I could use both monitors simultaneously (so the Retina screen would not be wasted), the iMac is faster than the base version Pro (at least according to the benchmarks) and the cost is between the other two (and not much more than my i7, 16GB 15" Retina MBP when I bought it). I am still waiting to see what the rumored 21" Retina iMac looks like but I assume I will go for the 27". Looking forward to it but waiting for Christmas or thereabouts.

Thanks to everyone for their help.

 

[pigoo3]

Looking forward to it but waiting for Christmas or thereabouts.

Since you have some time…don't forget to check out the Apple refurbished area. You will find 27" iMac's there in various configurations (and various vintages). If you want to find something special…you need to look often…since the stock can change rapidly. For a 27" iMac…you should be able to save $300-$350 vs. new. But…if you find something you like…you need to be ready to pull the trigger. Since again…stock can change quickly.

Sometimes the stock can include models from the lat 2-3 releases. And if it's been a while since the last release…you'll find refurb's of the current model release.

I just checked…and all the 27" iMac refurb's seem to be "i5" based at the moment (I think that you're looking for an "i7" iMac).

Good luck,

- Nick

 

[chas_m]

The question that hasn't been asked here is "what are you doing that you think you need 16GB or more?"

The "prevailing wisdom" for many years has been that you can never have enough RAM, but that is actually not true (and getting less true as time goes on). Barring some kind of professional use, 8GB should be fine for 90+ percent of users and typical use.

 

[MikeFromMesa]

The question that hasn't been asked here is "what are you doing that you think you need 16GB or more?"

The "prevailing wisdom" for many years has been that you can never have enough RAM, but that is actually not true (and getting less true as time goes on). Barring some kind of professional use, 8GB should be fine for 90+ percent of users and typical use.

I have 16GB of RAM on my MBP and I often find myself dropping below 50% available. Even now, when I am not doing much, my memory is at 69% available so I do not think that 8GB is sufficient for me. When I run Parallels (which is becoming very rare) it drops to 30-35% available. 16GB seems a minimum to me and 24 even better.

I am not doing anything "clever". I use CaptureOne or Optics Pro, both of which seem to use a good deal of memory, perhaps Elements or Affinity Photo, with a fair number of raw images loaded. I just seem to eat up memory and perhaps I have too many silent programs running, but I do use a memory cleaner and don't seem to have dead programs taking up my memory. If I look at what is running in the background the list is long, but they are not junk. Just normal stuff - Skype, photo programs, etc.

 

[chas_m]

Yes, if you're working with very large images (like RAW photos and such), lots of RAM is a good thing. However, I would add that the percentage of "free" memory you're seeing isn't actually an indicator of much of anything. OS X manages RAM extremely well, but keeps some of it reserved with recent applications (for example) or recent contents so that if you return to those things they load much faster. For example, open Safari with a pre-set page once, then quit it and open it again.

 

[MikeFromMesa]

Yes, if you're working with very large images (like RAW photos and such), lots of RAM is a good thing. However, I would add that the percentage of "free" memory you're seeing isn't actually an indicator of much of anything. OS X manages RAM extremely well, but keeps some of it reserved with recent applications (for example) or recent contents so that if you return to those things they load much faster. For example, open Safari with a pre-set page once, then quit it and open it again.

I just work under the assumption that, when in doubt, more memory is better than less memory. Not in extremes, but if I have to choose, I would choose 16GB over 8GB. I do not think that extends too far as I would not choose 32GB over 16 since I think it would be a waste of money, given what I use the computer for, but within reasonable limits I will always choose more rather than less memory.

I understand computer memory management and how the system tries to keep on top of what is happening and what might happen next to speed up processing, but unexpected stuff is handled better with more rather than less memory.

 

[alouellette]

Ram part numbers

I just work under the assumption that, when in doubt, more memory is better than less memory. Not in extremes, but if I have to choose, I would choose 16GB over 8GB. I do not think that extends too far as I would not choose 32GB over 16 since I think it would be a waste of money, given what I use the computer for, but within reasonable limits I will always choose more rather than less memory.

I understand computer memory management and how the system tries to keep on top of what is happening and what might happen next to speed up processing, but unexpected stuff is handled better with more rather than less memory.

Hello,

New to this forum and this subject caught my eye as I am in the process of purchasing a 27" Imac with Retina display. My plan is like many, purchase with 8g of ram and update from Crucial or OWC.

Can anyone post the links to the specific choices I have to complete this upgrade in 8g increments? I just want to be sure that I purchase the correct cards and have them available when the computer arrives.

Thanks

 

[pm-r]

You could start here and pick the iMac you would be purchasing and then do a page search on 'upgrade' for the various options they suggest:
http://www.everymac.com/systems/apple/imac/index-imac.html

Otherwise, I'm sure you can figure out how to access the two sites you mentioned, otherwise doing the upgrade and install may be a bit too much for you and you may want to have someone do it for you.

 

[alouellette]

You could start here and pick the iMac you would be purchasing and then do a page search on 'upgrade' for the various options they suggest:
http://www.everymac.com/systems/apple/imac/index-imac.html

Otherwise, I'm sure you can figure out how to access the two sites you mentioned, otherwise doing the upgrade and install may be a bit too much for you and you may want to have someone do it for you.

Thanks for the link..