From 4 to 8GB and worse results?

[mpts]

Hi there,

I got my iMac (27", i5 2.7, 4GB) just last week and today I installed additional Crucial Rams, 2x4GB 1333Mhz. So in total I have 12GB, and the About page on my iMac verifies that.

Well, I ran Geekbench last week and scored 7949 with approx. 6451 in memory performance. A link to last week's results http://cl.ly/8dch.

Then today, I ran Geekbench twice, the first time I got an overall score of approx. 7500 (don't have those results anymore, sorry). The second time I got 7920, but the memory performance is actually worse with a score of 6295. A link to today's results http://cl.ly/8dcs.

How is that possible? Did I install the Rams wrong so the older Rams are prioritised or something like that?

Basically, what I did was that the former Rams (2x2GB) used the top two slots and I placed the new Rams (2x4GB) in the bottoms two slots.

Thanks in advance!

 

[John T]

You did nothing wrong - apart from thinking that adding extra RAM will make your machine run faster!

You are not alone - many people don't realise that extra memory only comes into play when applications running on the machine demand it. This can easily be assessed by checking page-outs in the Activity Monitor.

Generally speaking, the 4GB of original installed RAM is perfectly adequate for the majority of users.

 

[mpts]

Ok, thanks.

Well, I didn't expect it to be faster, but I really thought that the benchmark scores would in some form display that the machine has more capacity.

I actually just got the rams because I do a lot photoshop, premiere and multitask a lot. So there they should def help me...I hope

 

[meli]

...the former Rams (2x2GB) used the top two slots and I placed the new Rams (2x4GB) in the bottoms two slots.

You may want to play with the order of the RAM modules. I've read contradictory reports, but on Crucial's site they recommend installing the larger DIMMs in the first slots because those slots are addressed first by the CPU.

slot 1: 4GB
slot 2: 4GB
slot 3: 2GB
slot 4: 2GB

On the other hand, as I read it, Intel says it's possible to achieve dual-channel mode with this configuration.

slot 1 (ch. A, DIMM 0): 4GB
slot 2 (ch. A, DIMM 1): 2GB
slot 3 (ch. B, DIMM 0): 4GB
slot 4 (ch. B, DIMM 1): 2GB

link: http://www.intel.com/support/motherboards/desktop/sb/cs-011965.htm#dual

Unfortunately, there does not seem to be any easy way to confirm if an iMac is running dual-channel mode. You can run Xbench tests with various RAM configurations and the results may lead you to the "best" configuration. Or you can install Windows, and using Bootcamp, run an application called Everest. That application will tell you if the computer is running dual-channel.

I'm not an expert on this, but perhaps you got a worse score after inserting the new memory because you disabled dual-channel mode by inserting the RAM in the order you did.

 

[AppleFan360]

You did nothing wrong - apart from thinking that adding extra RAM will make your machine run faster!

I don't necessarily agree with that. While the applications themselves don't run faster, switching between, starting them, and general navigation is quicker overall thus, the machine is "functioning" faster.

Also, if you have 12 applications open, you WILL be using swap at some point with only 4GB.

 

[mpts]

Ok, that's interesting. So I am def going to try and play with the order.
Btw...any hints on how to pull the Rams out of there? I tried it briefly with the ones there were pre-installed and it seemed like a pain in the ***.

 

[meli]

I don't have any hints for removing the RAM. But would you do me a favor and post any results you find in this thread? Thanks.

 

[mpts]

I will! Will try later tonight.

 

[meli]

Cnet has a video how to install RAM in the new iMac, maybe that will help:

http://howto.cnet.com/8301-11310_39...ll-ram-in-an-imac-video/?tag=TOCmoreStories.0

 

[meli]

I will! Will try later tonight.

mpts, did you get a chance to play around with the order of the modules?

 

[MR.Raul]

You may want to play with the order of the RAM modules. I've read contradictory reports, but on Crucial's site they recommend installing the larger DIMMs in the first slots because those slots are addressed first by the CPU.

slot 1: 4GB
slot 2: 4GB
slot 3: 2GB
slot 4: 2GB

On the other hand, as I read it, Intel says it's possible to achieve dual-channel mode with this configuration.

slot 1 (ch. A, DIMM 0): 4GB
slot 2 (ch. A, DIMM 1): 2GB
slot 3 (ch. B, DIMM 0): 4GB
slot 4 (ch. B, DIMM 1): 2GB

As Meli said, did you get to try out which configuration worked the best out of the two options posted by Meli?
Cause I'm curious as well, since I'm going to upgrade to 12GB myself in the near future.

 

[John T]

Also, if you have 12 applications open, you WILL be using swap at some point with only 4GB.

I also said "Generally speaking, the 4GB of original installed RAM is perfectly adequate for the majority of users". Running 12 applications simultaneously is hardly their behavior!