2.16 GHZ MBP Recognizing 4 GB RAM???

So, I decided it would be cheaper to upgrade my MBP than to get a new Mac. This is Brady's ridiculous sensible side.

Here is the situation: I bought a 4 GB RAM upgrade pack from NewEgg, and installed them along with a shiny new 200 GB 7200 RPM drive.

I bought the 2 x 2 GB set knowing that Intel chipsets address matched pair RAM better than a 1 GB + 2 GB setup. I fully understood that the 2.16 GHz C2D MBP should recognize a max of 3.3 GB of this RAM. HOWEVER, upon booting, the "About This Mac" pane shows the full 4 GB!

Upon further inspection, Activity Monitor also shows the system recognizing all 4 GB.

So, my question is pretty simple, yet I can't find an answer. Will the Mac show all of this RAM and just not address it all? Or did Leopard change the previous chipset limitations? Do I just have a super MBP? Help a guy out here!!!

If activity monitor sees 4 gig, then that's what is useable

I guess you are either lucky or just use a very smart memory supplier

louishen said:

If activity monitor sees 4 gig, then that's what is useable

I guess you are either lucky or just use a very smart memory supplier

Click to expand...

Very well!

Let this then serve as notice that if you have a NON Santa Rosa C2D MBP and install the 4 GB RAM kit from Kingston ($95 at NewEgg!!!), you should still see all 4 GB! Yahoo!

I love pleasant surprises.

Ack. Upon further examination, here is what I've found.

Activity Monitor shows a pie chart of memory according to usage, with the "Total Installed" memory beneath it. On my graph, this total is 4 GB.

However, when I add up the categories "Wired", "Active", "Inactive", and "Free", I get only 3 GB, which is what I was expecting. There is another category "Used", but this category is roughly equal to adding Wired, Active, and Inactive together.

So, I'm not sure which to believe...

If there is ANYONE on this board reading this thread with a Santa Rosa chipset-ed MacBook Pro that has 4 GB RAM installed, would you terribly mind posting a snapshot of your Activity Monitor in here? I'd love to see if they're comparable or if I actually only have 3 GB usable RAM and the system is just reporting a total of 4 GB installed and 3 GB usable, or if I am utilizing the full 4 GB.

Thanks a ton!!!

I think you only have 3.3GB. I have the same set up, but on my 2.16Ghz MB with the same results. It says 4GB everywhere I look, but only utilizes slightly over 3GB. On a bright note, I upgraded to 4GB from 3GB when the 2GB chip I bought for my Mac Mini would not upgrade it to 3GB (it was a core solo that I added a 2.16Ghz CPU to and just wouldn't make the hop from 2GB > 3GB). The MB is definitely quicker all around with 2 x 2GB chips than with 1GB + 2GB chips.

I am confused... and feel slightly dumb. You people know so much about computers (it seems). Why would having two different size RAM sticks not run as efficiently as two of the same size chips, even if it only uses the lower amount of RAM? 2+1 =3, 2+2 = 3 (because it only uses 3), yet 2+2 works faster? ... I'm just confused. I know nothing about hardware, which is what I really want to learn about, is there a good site? Thanks!

ogacon said:

I am confused... and feel slightly dumb. You people know so much about computers (it seems). Why would having two different size RAM sticks not run as efficiently as two of the same size chips, even if it only uses the lower amount of RAM? 2+1 =3, 2+2 = 3 (because it only uses 3), yet 2+2 works faster? ... I'm just confused. I know nothing about hardware, which is what I really want to learn about, is there a good site? Thanks!

Click to expand...

Short answer, if you're running dual channel, it's better to use matched DIMMs rather than unmatched. Better communication between the two, and therefore performance/speed. It just has to do with Intel's chipset architecture.

If I add Free, Wired, Active and Inactive I get my total RAM available to OSX. Hope that helps.

And dual channel means , double bandwidth,

The key limitations with any memory within any computer is bandwidth, the more you can load to the ram in a shorter space of time the more performance you will get out of it

a 2gb, and a 1gb would not operate in dual channel mode, thus leaving your probably worst of than having 2,1gb sticks, unless speed is not an issue as such and your working on huge psd's

by putting the 2 2gb sticks in dual channel fired up and it went faster!

And what a lovely first post

Thanks, everyone, for your replies.

It seems as though my previous excitement is unwarranted, my system is, in fact, only using 3 GB.

The computer recognizes that 2x 2GB modules are plugged in, but it can't get the non-Santa Rosa chipset to address any more than 3 GB. Oh well, I seem to be getting better performance anyway.