16GB vs 32GB RAM

Yes, but if you have to ask, your computational needs probably do not require that much RAM.

Also know, that if you get the 2012 27" iMac, upgrading RAM is easier and cheaper than going the Apple route.

I have a Mac with 32 GB RAM and it rarely is fully used unless I have more than one Virtual Machine (VM) open and After Effects rendering a preview and some other application also eating some RAM.

If you already have a Mac, open Activity Monitor and go to the System Memory* tab and look for Page Outs and Swap used and report back.

Using Activity Monitor to show you CPU and RAM usage​

* Mac OS X: Reading system memory usage in Activity Monitor​

 

Of course, it gives you the satisfaction that your computer is fully maxed out on RAM

 

I probably could have lived with 16Gb but I went all out for my 27" and got 32Gb.

Looking at the Activity Monitor I don't remember it going over 50% and I've had it 4 months now.

While I don't need 32Gb now but It's nice to know I won't have to buy and RAM for this iMac every.

 

You can do the same things as your computer will page out to the hard drive if you run out of RAM. If you reach that point, things will slow down but they'll still function.

At 16GB of RAM, it is unlikely you would be paging out to the drive. Most general users would be fine with 8GB or even less.

However, there are users like me who had to put in 32GB to avoid page outs and still have had 3GB of page outs since the last reboot. But my usage is far from typical.

 

4 gb = normal user/grandma checking email
8gb = power user/watching lots of video/gaming
16gb = super power user/ deceloper with 200 tabs and 3 development programs running
24gb = running multiple virtual operating systems
32gb = extreme cases

 

I went for 32 gb but after thinking about it I came to the conclusion that I wasted money. i could have just got 16 gb of ram and kept the 8 that i had for a total of 24 gb. that would have been more then fine.

for whatever reasons older ram is not always cheaper. in some cases its more expensive then new. so at least i know i got it for a good price. who knows what it will be a few years from now.

 

Old RAM i usually more expensive because of several reasons. It's not being made any more or not in great numbers, thus limited stock. Also newer RAM types use different methods which reduce production costs and since they are more current larger numbers bring down the price.

This doesn't mean the price will go up when they move onto the next RAM type but it might in a few years as supply levels come down again.

 

Adding 16GB to bring the system to 24 GB is a rather reasonable way to go for people who need more than 8GB but likely don't need more than 24GB. It still leaves the option open to replace the original 8GB if it turns out the do need 32GB and doesn't waste money.

In my case 8GB is a bit tight but I'm not sure I want to add memory to my old iMac, but I also know that I probably don't need more than 16GB, so in my case going to 24GB when I get a new iMac is all that I need to do and still leaves me room to grow if my needs change.

I'm actually glad there aren't many 4GB systems sold anymore. I've seen normal users open too many tabs and slow their system down.

As for gaming, 8GB is on the edge, especially if you tend to have a web browser, mail program, IM program and other stuff running at the same time.

 

If you are buying it, buy DDR3-1600. If you have it already, don't worry about it as you won't notice any difference unless you are benchmarking.

By the way, DDR3-1300 doesn't exist. And the 1333, 1600 etc numbers are not Hz! They are millions of transfers/second. A transfer in this case is 4 x the memory bus speed and 2 x (because it's double data rate) x 64 bits wide.

So 1600 x 4 x 2 x 64 x 1,000,000 / 8 = 12,800 MB/s Hence also called PC12800.

 

The 2012 iMac uses 1600Mhz, if you order online then just select the 2012 iMac and you should get the right RAM for the job.

 

I bought 16GB of RAM for my Mac Pro 5,1. I thought it would be enough, but I get page outs all the time (2-4GB per day). And my free memory is usually very low. So I wish I had bought 24GB or 32GB instead.

I don't get how 16GB is not enough, as I don't do anything out of the ordinary. The software I usually have open is Safari, Mail, Contacts, Notes, Calendar, iTunes, Mark/Space Notebook, uTorrent, Vuze, Skype, Dragon Dictate and one Win XP virtual machine in Fusion with 1.5GB assigned. Normal stuff.

 

I concur with you mate. On my 21.5" Haswell, it's only got 16GB of RAM and once I open up a VM to use AutoCAD, then it starts paging. I assigned 4GB to the VM. It also doesn't help that I have Photoshop CS6 open half the time. If only VMware or Photoshop was running, it'd be fine. But since I use both half the time, it's not fine at all.

The Haswell 27" in my basement server room, that's got 32GB of RAM and by far, that's quite fine so far, although with all sorts of things running, I last on just 2GB of RAM free on that machine.

But at least on the 21.5", it's okay paging because I went for a 256GB SSD, although slower, but still it's not as slow as paging with a 5400rpm drive.

 

Can't you just run the command purge?

 

At the expense of slowing down the entire system after the purge? It's unusable after a purge for systems with an RPM drive. Apps take ages to load after a purge.

 

Why is that exactly and it doesn't have an affect if there's an SSD instead of a hard disk?

 

Beats me, but I know that apps take forever to load (takes about a minute just to open up Safari) after a purge on an RPM drive.

Paging is like using hard drive space as a temporary form of memory. But note that accessing it from an RPM drive is a hundred thousand times slower than accessing from RAM, and accessing it from SSD is a thousand times slower than accessing from RAM.

 

Interesting. I guess the lesson is to be sure one has an enough RAM for his or her needs.

 

Quite right.

Basic rule when buying a Mac: If the RAM's soldered, go upgrade to the max possible.

If it isn't soldered, get the base one and buy RAM chips from other places at a much lower price. But just make sure that the CAS timings is suitable for the Mac.

 

If you open tons of windows with multiple tabs each in Safari like me, get 32GB. I regretted getting only 16GB in my new Haswell iMac with Fusion Drive.

5 days uptime and I'm getting the yellow Memory Pressure warning in Activity Monitor. -_-

 

I have 8Gb of RAM on my new iMac (spec bellow), and I had Google Chrome open with 2 tabs, iMovie open with a 1 hour 40 minutes video, Apple store, and iTunes, and I had no page outs, just 13Mb compressed. Very happy as that is more that I would normally ever do