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Level 1

15 points

Adding mismatched RAM on MacBook Pro ?

Hi,

I have a 2.0 Ghz MacBook Pro with the 512 MB Stock RAM that it came with.

I would like to add 1 Gig of Mac Compatible Corsair or other branded RAM.
Do I have to install matched RAM in this computer ?

Does it matter if the RAM I buy matches the brand of RAM already installed or if it is the same amount ? I am honestly really confused about this.

Ram prices are really low in Canada right now so I want to take advantage of this but at the same time, want to make sure that the $84.00 CDN that I am planning to spend on this extra 1 Gig will make a siginficant or at least noticable difference in my MBP performance.

Thank you for any recommendations or suggestions you may have.

Kallum

2.0 Ghz, 15" MacBook Pro, Mac OS X (10.4.7), 512 MB RAM

Posted on May 17, 2007 10:32 AM

42 replies

May 18, 2007 6:43 PM in response to KMoorehouse

Kallum,

You are soooooooooooooo welcome :-D

When there are questions about going from 2 GBs to 3 GBs (as in the new MBPs, which come with 2 GBs but support 3), I usually recommend that people stay with the default 2 GBs. This is because most people will never have a need for this much RAM (3 GBs, that is), and having Dual-Channel support would be way more beneficial than having unused RAM which does absolutely nothing for performance.

In your case, however, we're talking about a whole different kettle of fish. You see, OS X can run in only 512 MBs, but it really isn't enough to prevent "swapping" (having to read and write memory to the hard disk), even without running any applications. 1 GB provides all the space OS X needs to run without swapping, and there will be a bit of room left over for a few applications.

1.5 GBs, on the other hand, gives one enough memory to run OS X very well, to run several applications at once (still without swapping), and it provides one more benefit: Inactive RAM. This is where OS X "caches" instructions and data for applications you have run, but then quit. When you decide to come back to these applications, they respond (launch) in less than half the time. Once you get to 1.5 GBs, you will have enough RAM to maintain somewhere around 500 MBs of "inactive" RAM, and this will greatly speed up the (apparent) response of your computer.

To summarize, you will speed up your computer when you give it enough RAM to operate in most situations without swapping (1 GB). By giving it a little more (1.5 GBs), you provide an addtional boost by being able to maintain a significant amount of inactive RAM, which allows previously-used applications to launch much faster.

Scott

el-bo

Level 1

19 points

May 18, 2007 7:18 PM in response to KMoorehouse

sorry to hijack the thread

message for scott

hey

you mentioned about going from 2 to 3g on the mbp not necessarily being worth it

i have recently been considering doing this

my reasoning is that i own both an mbp (2.33, 2g) and an macbook (1.87, 0.5g)

my mbp is solely for music making, running logic pro and some power-hungry softsynths

i thought i could upgrade the mbp to 3 gig (purchasing a 2g stick) and then use the redundant 1g stick for my little macbook, pushing it to 1.25

i really will be able to squeeze every ounce out of the 3g in the macbook, however what you wrote made me think otherwise.....

the other alternative is to buy 2 x 2g (4g total) sticks for the mbp...i know this means only 3.25 useable, but i've heard it may run smoother down to the dual channel issues?????

it would also mean 2 shiny gigs for my little macbook

sorry for the rambling....what d'ya think ????

thanks in advance

KMoorehouse Author

Level 1

15 points

May 18, 2007 10:00 PM in response to el-bo

sorry to hijack the thread

Then why did you do it ? You say sorry to hijack it and then go ahead and do it anyway.

Please just start your own thread. It's a completely different question than the one I was asking.

KMoorehouse Author

Level 1

15 points

May 18, 2007 10:03 PM in response to el-bo

sorry to hijack the thread

message for scott

Hi Scott,

Could you possibly respond to this guy's question in a different thread ? I really don't like it when people hijack threads. They end up going off in a new direction and people stop giving feedback on the original question.

Thanks.

Kallum

May 18, 2007 10:52 PM in response to el-bo

el-bo,

Per Kallum's request, look for my separate reply in this same forum (Using your Macbook Pro).

Scott

KMoorehouse Author

Level 1

15 points

May 19, 2007 8:52 AM in response to Scott Radloff

Hi again Scott,

Kallum,

You are soooooooooooooo welcome :-D

Thank you 🙂

In your case, however, we're talking about a whole
different kettle of fish. You see, OS X can
run in only 512 MBs, but it really isn't enough to
prevent "swapping" (having to read and write memory
to the hard disk), even without running any
applications. 1 GB provides all the space OS X needs
to run without swapping, and there will be a bit of
room left over for a few applications.

This explanation is great. I really understand better now what is going on when that spinning ball is going and nothing seems to be happening.

1.5 GBs, on the other hand, gives one enough memory
to run OS X very well, to run several applications at
once (still without swapping),

This is going to be great !! On the basis of your recommendation, I went ahead and ordered a Gig of RAM and should get it next week. It will probably seem like a brand new computer after I install it. Right now, I can only run one or two apps at a time without the spinning ball starting.

and it provides one
more benefit: Inactive RAM. This is where OS
X "caches" instructions and data for applications you
have run, but then quit. When you decide to come
back to these applications, they respond (launch) in
less than half the time. Once you get to 1.5 GBs,
you will have enough RAM to maintain somewhere around
500 MBs of "inactive" RAM, and this will greatly
speed up the (apparent) response of your computer.

Excellent !!!!

To summarize, you will speed up your computer when
you give it enough RAM to operate in most situations
without swapping (1 GB). By giving it a little more
(1.5 GBs), you provide an addtional boost by being
able to maintain a significant amount of inactive
RAM, which allows previously-used applications to
launch much faster.

Scott

If I were to add another Gig of RAM down the road, to bring the MBP up to 2 gigs, would it add a further boost given that the RAM would then be maxed out ? or would it not be worth the extra money ?

It seems like I would already have a fairly significant difference going from the 512 MB to the 1.5 GB.

Thanks for all your help and assistance with this !!

Kallum

el-bo

Level 1

19 points

May 19, 2007 12:49 PM in response to KMoorehouse

easy now mr. m

i don't usually do it, however i thought i had been quite helpful with your question

i may have got details incorrect , but i was keen to help you find a solution

i only asked because my question was very similar......had we all been chatting in a room in the 'real' world, it would be quite appropriate for me to have asked....by apologising for hijacking , i was merely extending you a courtesy....i guess i'm not that sorry....

i'll leave you to your post

hope everything works out well

May 19, 2007 2:00 PM in response to KMoorehouse

Kallum,

Yes, you'll be tickled pink with the way your MBP will run, having 1.5 GBs. I think I need to mention here that, if you do still encounter any performance issues (SBBOD, etc.), you will need to look into the condition of your file system (I'm talking about disk errors, here, so don't worry about it unless it happens).

Down the road, going to 2 GBs will provide and additional boost to performance. In the past, with any G4 machines, I always recommended a maximum of 1.5 GBs. For most of us, there is, and never has been, any need for more ("power users" running Pro Apps being the exception).

With the Macbooks and Macbook Pros, however, there is the additional consideration of the availability of Dual-Channel mode across the memory bus. Simply put, when memory is installed in "matching pairs" of DIMMs (2 X 512 MB, 2 X 1 GB), the memory bus can operate with a higher data throughput, due to the way the memory can be accessed. This increase in the amount of data that can be moved around on one clock cycle amounts to a significant performance increase; enough to warrant adjusting one's memory to enable this mode. Since 1.5 GB is the "sweet spot" for OS X, this means that one must go to 2 GBs (2 X1 GB) to get both the benefit of ample RAM and the boost from Dual-Channel mode.

Go to 2 GBs when you can.

Scott

KMoorehouse Author

Level 1

15 points

May 19, 2007 2:53 PM in response to el-bo

easy now mr. m

i don't usually do it, however i thought i had been
quite helpful with your question

i may have got details incorrect , but i was keen to
help you find a solution

Hi El Bo,
BTW - I am female so not a Mr 🙂
I'm sorry the way I came across. I was just trying to get as much information as I could on this situation or question I had so I wouldn't make an expensive mistake.

I was afraid that by changing the direction of the discussion, any other possible contributions might be deterred.

I did appreciate your help though. I just got a tiny bit upset when the thread got hijacked.

Thank you for your note and your assistance,

Kallum

KMoorehouse Author

Level 1

15 points

May 20, 2007 11:11 AM in response to Scott Radloff

Hi Scott,

Kallum,

Yes, you'll be tickled pink with the way your MBP
will run, having 1.5 GBs. I think I need to mention
here that, if you do still encounter any
performance issues (SBBOD, etc.), you will need to
look into the condition of your file system

I am sooo excited about installing the extra RAM. I can't wait to see the difference and STOP seeing the spinning ball !!

Down the road, going to 2 GBs will provide and
additional boost to performance. In the past, with
any G4 machines, I always recommended a maximum of
1.5 GBs. For most of us, there is, and never has
been, any need for more ("power users" running Pro
Apps being the exception).

How much of a boost would I see with adding another 1 Gig to bring it up to the full 2 GB of RAM ? Will it be as noticable as the jump from 512 MB to 1.5 GB ?

If I decide to do this, does the second RAM chip have to be exactly the same brand etc as the one I will be installing this week for the dual channel mode to kick in ?

With the Macbooks and Macbook Pros, however, there is
the additional consideration of the availability of
Dual-Channel mode across the memory bus. Simply put,
when memory is installed in "matching pairs" of DIMMs
(2 X 512 MB, 2 X 1 GB), the memory bus can operate
with a higher data throughput, due to the way the
memory can be accessed.

Okay - By matching pairs, it is size, not brand.
This so cool. I knew this was a great computer when I got it but I don't think I have ever really pushed it to it's full potential.

When the dual channel mode is enabled by matching RAM, will it be more noticable in apps like Photoshop (loading rendering) or in using and switching between multiple open applications - or both ?

Thanks again for all your help with this. I am just trying to gain a better understanding of dual channel mode and how to maximize the potential of this computer.

Kallum

May 20, 2007 11:49 AM in response to KMoorehouse

Kallum,

Yes, you will notice an additional increase in speed if/when you upgrade to 2 GBs. Certainly not as much as you will notice this time, going above that horrid 512 MBs, but palpable nonetheless.

Mostly, this "boost" (when you go to 2 GBs) will be in raw horsepower. When Dual-Channel mode is enabled, both banks of memory can be addressed simultaneously, for greater data throughput to the processor. This makes everything run moe efficiently, thus speeding the computer. Right now, you are concerned with giving it enough RAM to operate normally without swapping.

A good analogy would be having an auto that runs poorly. Right now, you want to fix it enough that it stops stalling every time you come to a stop sign, causing you to take time to get it running again every minute or so. In the future, you will have gotten the car tuned up and running smoothly, but you will add a turbocharger to make it go faster.

When Dual-Channel is enabled, just about everything will be faster to some degree. Of the items you mention, things like rendering will be most affected. The more something depends on data being moved into and out of RAM quickly, the more it will benefit.

For more info on the effects of various amounts of RAM, have a look at my response to your friend el-bo, in this same forum (titled "for el-bo").

Scott

KMoorehouse Author

Level 1

15 points

May 21, 2007 10:30 PM in response to KMoorehouse

Hi,

I would like to thank everybody who helped me with my RAM questions. I am anxiously and excitedly awaiting the 1 Gig that I ordered. It should arrive this week.

I am really hoping the prices stay low so that I can purchase another gig when I get some more money at the end of the month. However, we'll see how it goes with the 1.5 Gigs.

I'll definitely let you all know once I install it !!!

Kallum

Adding mismatched RAM on MacBook Pro ?