I'm coming from a PC, loaded with a Core 2 Quad CPU and 8GB of DDR2 RAM. I was running Premiere CS3.

I'm new to Mac so I'm not sure if this will help performance: Will increasing my 21.5" Core 2 Duo iMac's memory from 4GB (DDR3) to 8GB improve performance of Premiere CS4 significantly? I am not impressed with Premiere as it is now. The iMac is the newest one as of this post.


Yes! Mac OSX loves RAM and so does Premiere. Max out the memory if performance is important to you.

Do you "need" 8GB or 16GB? As others suggested, best thing to do is look at memory usage during actual usage. Without upgrading, it might be hard to tell but give it shot. A couple nice articles about OSX memory and performance might be worth reading: Problems with lack of memory in OSX & OSX Performance Tuning

I couldn't find a definitive answer, so please verify, but I think you can add 2x4GB SO-DIMMS giving yourself 12GB. That would let you upgrade without having to throw away your upgrade later if you do upgrade to 16GB. Unfortunately, there is currently a significant price premium for the 4GB SO-DIMMS.

Lastly, if you have the GeForce 9400M version of the 21.5" iMac, chances are good you'll see a large boost from 8GB since your video is sucking up system memory.

  • Will it run smoothly with 8GB or 16GB? – Moshe Apr 1 '10 at 16:01
  • Moshe - It's hard to say whether you need 16GB, or just 8GB. It really depends on how much you need. That said, you can never have too much RAM. – jerwood Apr 2 '10 at 3:52
  • @ipaulo - I have the Radeon HD version of the iMac. – Moshe Apr 2 '10 at 19:12

Open up Activity Monitor (it's in Applications/Utilities) - select the Memory option - run the program you're interested in (Premiere) - stress it as much as you can. If you still have a green segment (unused RAM) then you don't need to add any more RAM.

  • 1
    Although you might want to consider fluctuations, e.g. one might be using a whole lot more RAM later after one checked the Activity Monitor. In other words, do thorough testing to make sure you really have enough. – Nathaniel Apr 2 '10 at 0:27
  • @Nathaniel: yes, that's what I meant by stress it as much as you can – Paul R Apr 2 '10 at 10:22
  • Whoops. I think I might have missed that. Sorry. – Nathaniel Apr 2 '10 at 21:18
  • @Nathaniel: no problem - it's easy to miss details when you're "speed reading" ;-) – Paul R Apr 2 '10 at 21:47
  • @Nathaniel Must have a lot of RAM in him. :-) – Moshe Dec 7 '10 at 5:30

More RAM will always improve performance... or cause the OS to go crazy. One of those.

Well, okay, if the OS can't make any use of it (because it does not fit in the physical address space supported by the OS, for example), it won't do anything, it's true, but...

  • The question was if performance will be improved significantly. Which is debatable starting at 4 GB.. – akid Apr 1 '10 at 22:35
  • @akid - Well, I'm doing motion graphics related activity which can never have enough memory. I'm just new to Mac and all, hence the question. – Moshe Apr 2 '10 at 0:51
  • @akid - btw, Mac OS X is slow at certain points on 4GB of RAM. (Logging back in, for example) Start up is long too... – Moshe Apr 2 '10 at 1:11
  • @Moshe - I get that. I was just pointing out that although correct, this answer doesn't help you a lot in determining if an upgrade is worth the cost and effort. – akid Apr 2 '10 at 8:17
  • @akid. - True. I hear you. – Moshe Apr 2 '10 at 15:12

As mentioned by Paul R, it's worth checking Activity Monitor to see how much RAM is actually in use and whether or not more RAM will help. Premiere CS4 is not 64-bit on Mac OS X, Premiere itself can not use more than 4GB of RAM on it's own.

The biggest advantage of having more RAM is that it allows you to switch between programs without requiring to page in or out memory from the hard drive. The hard drive is often times the bottleneck when it comes to speed. (eg. Your comment to SamB's answer re: Mac OS X slow at start up, logging back in, etc. is all the hard drive speed and not the amount of RAM at that point).

Mac OS X loves RAM and will use up as much as possible before touching the hard drive for virtual memory. I'd recommend upping the RAM as the speed difference in switching applications and not having to worry as much about disk swapping makes life much easier. How many other programs are you running at the same time? If you're running more than 2 or 3 you should notice a difference. But to determine a significant improvement it's difficult without knowing the amount of RAM Premiere is actually using (eg. Final Cut Pro isn't a RAM hog - it's constrained by other factors first) and whether or not the competition it has for RAM is actually causing a performance penalty.

  • Actually, when running PRemiere, I shut everything else down for memory's sake. I wonder if a reboot would be better... – Moshe Apr 2 '10 at 15:13
  • @Moshe: A reboot would be better if you're wanting to squeeze every possible byte available (as it will reduce the amount of the OS libraries loaded because of other programs). – Chealion Apr 2 '10 at 20:13

I always watch the RAM usage and after upgrading a mid 2010 iMac 27" from 4GB to 12GB, I could not see any improvement or the system making use of the added RAM.

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    Do you mean it used up the RAM without any noticeable change, such as faster fps? It's likely it was already fast enough animations. – tobylane Jul 14 '11 at 14:13

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