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Decisions decisions 12GB or 16GB?

BasilFawlty

BasilFawlty

macrumors 65816
Original poster
Jun 20, 2009
1,082
3,040
New Mexico
Ok, I have a new i5 27inch iMac that came with 4GB memory. On a few occasions I've felt I needed a bit more. I will probably get my memory from OWC, and have two choices. 1. I can replace existing 2x2GB cards with 4 x 4GB for 16 GB for about $115, or I can keep existing 4GB and add 8GB more for total of 12GB for $58. I'm leaning towards just getting two more 4GB (8GB ) and upgrading to 12GB for $58, with the idea that 12GB will be more than sufficient for a while. Later (in a couple years) the price of two 4GB cards will likely come down and I can upgrade further then. My only (minor) concern is that I've heard that these memory are "dual channel" and you loose the dual channel aspect of the memory if you have mismatched cards (2x2 and 2x4) rather than the same size in all slots. NOt sure how accurate that is? If it is true, I'm not sure what that loss of dual channel will mean in practical terms, but I'm guessing for what I do, not much. Thoughts?
 
You have two dual channel setups, with two 4GB and two 2GB sticks. And even if it would not be a dual channel setup, the gain from dual channel is less than 10% performance, hardly noticeable.
Btw, you can get two 4GB sticks from Newegg for less than 50USD, thus 16GB would be less than 100 USD.
 
12Gb has been plenty for me

I picked up a 27" i5 iMac at the weekend and had it upgraded to 12Gb RAM (they used Kingston for the upgrade). It absolutely flys and I cannot see how I would ever need more than 12Gb.

I have checked the system a couple of times and it seems to have around 7Gb idle, so I'm only scratching the surface at this point.
 
I have 12 gigs in mine and I definitely notice the difference it makes. For now it's sufficient for me, you may be different!!!
 
RobTownshend said:
I picked up a 27" i5 iMac at the weekend and had it upgraded to 12Gb RAM (they used Kingston for the upgrade). It absolutely flys and I cannot see how I would ever need more than 12Gb.

I have checked the system a couple of times and it seems to have around 7Gb idle, so I'm only scratching the surface at this point.
Click to expand...

Thanks for the feedback. I think I'm going to order 8 GB (2x4) and upgrade to 12. If someday I need more I guess I can always buy more (and it will probably be even cheaper by then).
 
BasilFawlty said:
Thanks for the feedback. I think I'm going to order 8 GB (2x4) and upgrade to 12. If someday I need more I guess I can always buy more (and it will probably be even cheaper by then).
Click to expand...

I got 12 as well. The way I look at it, I can pay $50 for 8GB of RAM, but it wasn't worth it to pay another $50 for only 4GB more.
 
It all depends on what you are using that RAM for. If it's video editing, get as much as you can. If you just want a performance gain from a RAM upgrade then 12 is enough and is a lot cheaper!
 
Unless you actually use the extra memory it makes no speed difference on your Mac. Your Mac does not "go faster" because you added more memory to it. It just goes farther before paging out to the HDD (which slows you down). Just FYI as some posters are seeming to allude to this.
 
Yes, go to 12 now, but when 12 becomes insufficient you can go to 32, which will be reasonable in a couple of years.
 
derbothaus said:
Unless you actually use the extra memory it makes no speed difference on your Mac. Your Mac does not "go faster" because you added more memory to it. It just goes farther before paging out to the HDD (which slows you down). Just FYI as some posters are seeming to allude to this.
Click to expand...

As per this poster, check how much you actually need during your normal use/workflow in Activity Monitor. Search for threads about reading the Memory tab and "Page ins" and "Page outs".
 
I agree with a few other posters...

Load up your iMac with your heavy memory usage apps / data. When the iMac system feels its getting "sluggish", perform:

Look at its Applicaitons - Actvity Monitor - CPU usage. If CPU usage if often > 80% on a consistant basis, then its enduring CPU starvation. If CPU usage is often < 80% during sluggish time, then its a different bottleneck area. If consistantly above 80% usage, upgrade with faster CPU.

Is it starving for more physical memory? To answer this question, use Applications - Activity Monitor - Memory usage panel. Focus on page ins/page out, apply an industry standard ratio and throw in a "gut feel". Then, make the decision if more physical ram is needed. To help decide if memory bottleneck, simply look at its Free memory stats. If "under load" single number is < 500 MBs, then more physical memory is required. If number is > 500 MBs, then more physical memory is NOT required. Yes, it's more complex then this single value. But for single number decision, FREE Memory of 500 MB threshold value works as well.

If "on the edge" of physical memory starvation, I'd buy more memory for $58. re: "add 8GB more for total of 12GB for $58". Especially since memory is low cost these days...

Hope this helps...
 
12 gb

BasilFawlty said:
That's kinda how I'm leaning right now.
Click to expand...

Should be enough for you, and you won't waste modules doing it that way. I have a 27" I7 that came with 8GB, but do a lot of video rendering etc. so I upgraded to 16gb. Eats everything I throw at it now.

I went for the 2GB graphics option too, so this iMac should last me a good long time.
 
Ok, I've decided to go with an additional 8GB (for 12GB total) after looking at benchmarks for Photoshop that OWC has posted (and I use PS a bunch). For the benchmark tests they used, the time was about cut in half with 12GB compared to my stock 4GB. However, very little additional improvement (at east in this benchmark test) with 16GB.

Question for those who have made a similar upgrade: Did you see any improvement in rip times for Handbrake? I'm slowly going through my vast DVD collection and ripping and it would be nice is this upgrade would speed up that process.
 
BasilFawlty said:
Ok, I've decided to go with an additional 8GB (for 12GB total) after looking at benchmarks for Photoshop that OWC has posted (and I use PS a bunch). For the benchmark tests they used, the time was about cut in half with 12GB compared to my stock 4GB. However, very little additional improvement (at east in this benchmark test) with 16GB.

Question for those who have made a similar upgrade: Did you see any improvement in rip times for Handbrake? I'm slowly going through my vast DVD collection and ripping and it would be nice is this upgrade would speed up that process.
Click to expand...

As far as I know Handbrake is CPU intensive, not RAM intensive.

And about that benchmark...keep in mind that you are not going to have only photoshop running, you will have more applications running at the same time consuming part of the available RAM for photoshop
 
At this point there isn't much of a difference between 12gb and 16gb, while the jump from 4gb to 12gb is huge. The smart move is to go to 12gb IMO.

As for the brand, I wouldn't overpay for OWC. I've been using Corsair memory for almost 15 years, they make great products that come with a lifetime warranty. I just picked up these bad boys a few days ago:

http://www.amazon.com/gp/product/B002YUF8ZG
 
As an Amazon Associate, MacRumors earns a commission from qualifying purchases made through links in this post.
I bought this on eBay for $85, and it has worked perfectly since installing. Received it within a few days, and had it installed in five minutes.
 
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