6gb ram in imac late 2007

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6gb ram in imac late 2007

I just bought the 6gb kit from OWC and installed in my santa rosa imac 7,1. Everything runs fine. But I decided to run a benchmark to see if there was any difference from my 4gb kit. I wasn't really suprised but the 4gb kit from OWC beat the 6gb kit big time. I did the same test with geekbench both 32 and 64bit 5 time with each set of RAM and the 4GB kit won. The memory bandwith was a lot higher with 4GB and the memory performance was better with 4GB. Is this due to the 4GB being dual channel and latency 4 and the 6GB being latency 5 single channel or does the imac just like 4 better than 6 meaning is it not capable of using all 6gb of RAM. I am running snow leopard and all 6GB show up in activity monitor and iFreemem app. Please give me your opinion on this.

imac 7,1, Mac OS X (10.6.2)

Posted on Feb 19, 2010 9:27 PM

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Answer 1

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den.thed

Level 9

77,176 points

Feb 19, 2010 10:10 PM in response to spookmag

Hi spookmag

It's really not surprising that the matched set bench's slightly faster, the only real benefit in 6GB is when your are running multiple applications that use more than 4GB.

This same effect in reverse was probably more noticeable on the earlier models that had a 3GB ram limit with 2 matching 2GB modules installed in it.
http://guides.macrumors.com/UnderstandingIntel_MacRAM

Ever wonder why OWC doesn't include the 6GB results on there Performance Test page? 😉
http://eshop.macsales.com/shop/MemoryBenchmark/AppleiMac/

Dennis

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Answer 2

PJB

Level 2

365 points

Feb 20, 2010 12:04 AM in response to spookmag

You shouldn't be surprised that in synthetic tests, dual channel memory will outperform single channel memory.

In the real world, if you are using more than 4GB of RAM, 6GB will still be faster than your hard disk.

Much ado about nothing, methinks.

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Answer 3

spookmag Author

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Feb 20, 2010 12:09 AM in response to PJB

"Much ado about nothing" are you Jar Jar binx? Thanks for your opinions.

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Answer 4

froggy18

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Feb 20, 2010 7:02 AM in response to PJB

PJB - so is the case from what the previous poster said that 6 may be the same or a bit slower when using less than 4, but speed kicks in when apps suck up more than4? I am moving from 2 - will I see a difference with 6 when running, multiple ram hogs like FC & Aperture?

Message was edited by: froggy18

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Answer 5

spookmag Author

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Feb 20, 2010 7:48 AM in response to froggy18

those are the apps that I am running. Mostly Aperture 2/3 and CS4. I have noticed a little faster HDR photo generating when using the 4GB C4 dual channel RAM over the 6GB 1x4,1x2 RAM in my iMac.

Aperture 3 is 64bit now and uses a lot more RAM but is slower with 6GB than it is with 4GB.

Message was edited by: spookmag

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Answer 6

Feb 20, 2010 8:03 AM in response to spookmag

You don't move from 4GB to 6GB to make ONE application run better.
*You add memory so you can have more applications open and running at the same time.*

For example, in my case, developing a website using: Dreamweaver, Illustrator, Photoshop, Firefox, Mail and some utilities. Then I need to launch VMware Fusion to check the website I am working on in IE8. Having 6GB makes all the difference in using Fusion.

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Answer 7

spookmag Author

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Feb 20, 2010 9:37 AM in response to Community User

i understand that, but I was just giving an example of the difference in performance I am getting with a memory hog app like Aperture 3. This app is 64bit and an access all 6gb of ram if needed. but 4gb runs better with this app than 6gb. This is what concerns me. Why would more ram run slower than less ram. Aperture access less virtual memory with 6gb than 4gb yet still runs slower at every day tasks. As for your point, I can run CS4, aperture 3, vmware fusion with windows 7 64bit, safari, and quicktime x (with a 1080p hd movie playing) with 4gb of ram smoothly, but not with 6gb. I get the spinning wheel with 6gb after starting about 3 of those apps and never with 4gb.

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Answer 8

Dah•veed

Level 9

64,651 points

Feb 20, 2010 11:56 AM in response to spookmag

Wow, now it is getting interesting. We have just had +Dave Barnes+ in the past telling us that it works. But we get some real world comparisons with spookmag also having the physical hardware as well.

Stay tuned fans for the next chapter of +*RAM Smackdown*+ - 4 GB Matched (2 x 2 GB) vs 6 GB unmatched (2 GB + 4 GB) modules.

Dah•veed

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Answer 9

PJB

Level 2

365 points

Feb 21, 2010 1:41 AM in response to froggy18

If your computer is paging heavily with 4GB RAM, then 6GB will almost certainly speed things up. You can check this by looking at the page outs (disk writes) in system monitor. If the number increases dramatically over a short time, you are running out of RAM.

You could also manage your workflow better, like keeping the number of open applications down to a minimum, especially when you are using memory hungry software.

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Answer 10

Feb 21, 2010 2:37 PM in response to Dah•veed

I compete in the "Completo" class of Lucha Libre.

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Answer 11

froggy18

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Feb 21, 2010 7:21 PM in response to PJB

Thanks PJB.

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Answer 12

spookmag Author

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Feb 21, 2010 10:57 PM in response to PJB

Did you not read my first post PJB? 4gb is faster than 6gb. I'm not worried about page outs. when I run 4gb every thing is smooth. when running 6gb it crawls. I ran all those apps to test this. I only use aperture or CS4 one at time and maybe photomatix hdr software. My impression of ram is that the more the better. So for the 4th time, why is 4gb faster than 6gb? Is it because of dual channel? Is it because the 4gb is low latency c4? These are the questions I am asking for peoples opinion on, Not how to manage my app usage. I am a professional photographer who has been using iMacs and Mac pros for years and have never ran into a problem like this before. Hopefully when my new 8 core mac pro with 16gb of ram gets here I won't have to worry about this. But right now I'm just curious as to what is causing this issue.

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Answer 13

PJB

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365 points

Feb 22, 2010 1:50 AM in response to spookmag

I was responding to froggy. I was also comparing 6GB RAM vs hard disk, not 6GB RAM vs 4GB RAM, hence the remark about page outs.

I've no idea why 4GB is faster than 6GB. I can't afford a 4GB stick, so there's no way I can confirm your findings either way. Dual channel memory supposedly only makes a difference of about 10% in speed (i.e. you won't notice it).

You could try doing a fresh install on an external HD with the 6GB, but other than that, it beats me.

Have you tried the Apple hardware test?

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Answer 14

den.thed

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Feb 22, 2010 4:40 PM in response to spookmag

I'm sure that the difference in cl=4, 5 or 6 has a lot to do with the overall performance that you are seeing in both the bench test and practical use.

The spec's for the [4GB OWC kit|http://eshop.macsales.com/item/Other%20World%20Computing/5300DDR2S4GB> say they are cl=5, where did you get your 4GB cl=4 kit?

Apple's [RAM Expansion Product-Specific Details|http://developer.apple.com/legacy/mac/library/documentation/HardwareDri vers/Conceptual/HWTech RAM/Articles/RAMimplementation.html] say's the CAS latency for:
+iMac Computers (April 2008) support a CAS latency of 5 or 6+
+iMac Computers (August 2007) support a CAS latency of 5.+

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Answer 15

Feb 28, 2010 3:58 PM in response to den.thed

I have 3GB in mine and was considering the 6GB upgrade. I mostly use my iMac to edit photos but occasionally I run VMware 2.0 and Windows XP for some gaming. This kills the computer. I would love to know what benchmark software the OP used so I can do some tests on mine under a load.

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