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Upgrade from 4gb to 8gb RAM?

Is there a noticable performace improvement on a dual core iMac between 4gb and 8gb? I am wondering if a dual core can actually utilize 8gb of RAM or if the last 4gb would essentially go unused.

iMac, Mac OS X (10.6.4)

Posted on Jun 24, 2010 10:33 AM

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7 replies

Jun 24, 2010 7:56 PM in response to Hearnje

John,

Welcome to Apple Discussions!

The performance gained by adding RAM (assuming your machine can be upgraded to 8 GB) is totally based on how you use your computer. So without any knowledge of what applications you run and how taxed your machine is now no one can really answer your question. In other words please give us more data! If you want to see how taxed your machine is, run Activity Monitor when your machine starts slowing down and see what is taking RAM and CPU.

Regards,

Roger

Sep 9, 2010 12:50 PM in response to Hearnje

If no one minds, I'd like to pick up this question where it left off. I'll give as much information about my system as I can, as well as what I use it for. Being "self-taught" on FCP and Compressor, I'm well aware that there's much I don't know.

I have a late '09 iMac - 3.06 GHz Intel Core 2 Duo: 4GB 1067 MHz DDR3. Mac OSX 10.6.4.

I am shooting HDV and AVCHD video (some DV as well) and using FCP 7.0.2 to produce short and long videos, accompanied by Compressor.

My "Memory" shows only two banks (Bank 0, Bank 1), each with 2GB... does this mean I only have two slots total for RAM? I thought "empty" banks would show up here, as well.

To Barbara ... I'm not sure how to see in "Activity Monitor" how much RAM my iMac will allow. I know that it's at least 4GB, because it regularly gets near that when I run Compressor and FCP at the same time. But in light of your question, how would I check to see if my iMac would even allow more RAM?

As far as what I can tell from my system's performance... in general, sometimes it runs great... sometimes my FCP projects render very slowly.

As stated, when running Compressor and FCP together I can see in my Activity Monitor that I get into the 3.8's in terms of "used" memory. There are several hundred Megs that are "Inactive", though I have no idea why. My "Free" memory gets very low.

I think I read in a similar thread to look for "Swap used". That runs about 400 - 600 Megs. I'm not sure what that means. Is it as simple as other processes that are being ignored at the time in favor of something else? Just a guess.

Is there any other information you need?

I'm open to suggestions on how to optimize my iMac's performance. Not that it's completely terrible now... but time is money and if I can cut minutes from time spent rendering/compressing, I'm all for it.

Thanks!

Sep 9, 2010 1:04 PM in response to Von Pickler

what you really need to consider is the "page outs" in activity monitor and how high they are compared to page ins. If your RAM never gets filled up that value is normally very very low, <1% of the page ins. They say if the page outs are about 20% of the page ins that's still ok, but I would consider that way too high.

anyway, do your normal work on the mac (after rebooting the page ins and outs are reset) and then look at those numbers, they clearly tell you if you need more RAM.

just to explain:
page outs are the number of pages (data from RAM) that has been written to hard disk. this happens mostly when the RAM is full, and when it happens a lot it slows down everything very significantly.
page ins on the other hand is data written from RAM, so you could say it tells you how much your RAM "works". so if you compare those, you can tell how much of your RAM has to be swapped to the hard drive. if it's a lot (I would consider 5% page outs compared to page ins a lot, others would maybe disagree) than more RAM will be useful.

Sep 9, 2010 2:22 PM in response to Hearnje

That's interesting. Thanks, Nach...
So, I looked at Page Ins/Outs and here's what I saw.

After a morning of running FCP and Compressor, I read your post and checked the Ins/Outs. It said:

INs: 501.8
OUTs: 215.7

To be fair, I was running other applications, too (Safari, Open Office)

As you said, I re-booted and the pages re-set to:

INs: 150.0 MB
OUTs: 0

After starting FCP and Compressor again and exporting (FCP) and Compressing at the same time with Safari open, it went up to:

INs: 250.7
OUTs: 0

"Used" memory never shot above 1.85 GB... a drastic difference from what I experienced before. Clearly, something was chewing up RAM before, but I have no idea what it could've been.

Any thoughts or insight? I appreciate it.

Sep 9, 2010 3:14 PM in response to Von Pickler

501 to 215 (I guess MB?) is clearly a weird ratio. 0 sounds much more like it 😀
I would just keep a look at it, especially when you feel your imac is running sluggish. if page outs increase in these times, then a RAM upgrade might give you a performance boost.

also, be careful when looking at the used RAM in activity monitor: it counts together wired, active and inactive RAM, which is a little weird, because inactive RAM is actually RAM that can be used by the system. basically, you can count inactive RAM towards free RAM.
inactive RAM works like this: application A is used, writes stuff into the RAM. if you quit the application the RAM it used goes towards inactive RAM. if the system needs that inactive RAM (because you start another app B), it throws out what app A wrote and uses it. but if app A is started and the stuff it wrote to RAM is still present, it can reuse that and start much faster.
long story short: inactive RAM can be used by the system when needed and is therefore the same as free RAM.

Upgrade from 4gb to 8gb RAM?

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