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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

KMoorehouse Author

Level 1

15 points

May 17, 2007 10:07 PM in response to L0K13

It is an apple compatible product. I have used them
for years and returned RAM that went bad (only once)
with zero issues. I am the IT director at work and
use them for RAM there as well.
How much would you estimate the tarrif would be to
have this shipped FedEx?
I would alway use matching RAM in any case. If you
need to get another 512 it would handle most things
faster than mismatching with a different size simply
because of the dual channel support it would enable.

Hi,

Thank you very much for your reply. I didn't realize that it was as important to match the RAM on the older MBP's as the new ones.

I would be thrilled if just adding 512 MB would give me the same boost as adding the 1 Gig the unmatched 512 MB though!!! Would it ?

Does it matter if the RAM I buy is the same brand or it the size that they are referring to in the matched pairs.

Regarding the tarrif on the RAM - anything that comes across the border via courier can cost quite a bit. We have to pay all applicable taxes (not a big deal as we pay $13 % in Fed and Provincial sales taxes here anyway) and some sort of charge for bringing it across the border and this can depend to some degree on the courier.

USPS is usually much better for us and whenever I buy on eBay from Americans, I ask for shipping by USPS vs any kind of courier.

Thanks for all your help and suggestions !!

Kallum

el-bo

Level 1

19 points

May 18, 2007 5:18 AM in response to KMoorehouse

just add my two pennies worth

1) i have read countless times that the increase in performance by adding extra ram far outweighs the compromises made from mismatching

2) sorry if this is wrong, macbooks with 512 ram are already matched pairs..as in 2 seperate blocks of 256.....adding a 1g block to replace one will mean a total of 1.25g or .75g if you add the half gig block

at todays low prices (try owc) 2gig is a great value add-on if you can stretch to it....

el-bo

Level 1

19 points

May 18, 2007 5:24 AM in response to el-bo

so just to clarify

the only way to match both sides would be to buy 2 x 1gig blocks or 2 x 512 blocks....either way you would have to ditch the 2 blocks you have

i wish i coud point you to the performance tests that show mismatched ram to be not much of a compromise, but anyway.....i would say that if you can afford only 1 gig, get it and enjoy 1.25....if in the future you can afford it, it will then be easier to add an extra gig to replace the 256

el-bo

Level 1

19 points

May 18, 2007 5:54 AM in response to el-bo

may have spoken too soon...thought we were talking about macbooks ( not pro)..wrong forum i guess

so just check how your macbook is configured mine has 2 gig matched and i'm considering mismatching a 2g and 1g myself (3g total....wooohooo)

L0K13

Level 1

0 points

May 18, 2007 7:16 AM in response to KMoorehouse

Kallum, the last post brings up a good point. I have been operating under the impression that you have a single 512 chip. After reading the last few posts this morning, I went back and read them all. I suspect that you indeed have two 256 chips.

To check this, go to the Apple menu on the upper left of the desktop. Choose About This Mac from the menu. In the resulting dialog box click More Info...

Under the Hardware section on the left side, click Memory. If you see two DIMMs here reporting to have a size of 256 MB each, then you are probably going to want to rethink things a bit. There are only 2 slots and you will be giving up one or both of the 256 chips to make any upgrade. (keep them in a static bag or case as they will be used in the event that your new RAM ever goes out and you have to swap them for a warranty replacement).

It will be to your advantage to stick it out till you feel you can afford to buy two 512s or two 1gig chips.

L0K13

Level 1

0 points

May 18, 2007 7:40 AM in response to KMoorehouse

So far as the matched pairs...

When they use the term matched pairs, it means that they are selecting RAM made at the same general time on the same production line. When they make RAM it is created in lots. The lot size depends on the vendor order but each lot it made to the same specs. The next lot may vary on specs slightly and still carry the same model number. You can identify the lot by the long alpha numeric code on the chip (or before you buy it should be listed on the website of the vendor). This lot number can generally be located on the manufacturer site and compared with all other chips bearing the same model number from that manufacturer.

Is all this really needed? Well maybe not to a certain degree. It would be good to verify that you are purchasing the same RAM by at least matching the numbers on the vendor site. The ones who have been in business longer will invariably offer up the serials on any RAM you may be viewing. Same serial = same batch of RAM. You should see less unexplained errors, lockups etc if you verify the numbers before purchase.

KMoorehouse Author

Level 1

15 points

May 18, 2007 8:02 AM in response to el-bo

i wish i coud point you to the performance tests that
show mismatched ram to be not much of a compromise,
but anyway.....i would say that if you can afford
only 1 gig, get it and enjoy 1.25....if in the future
you can afford it, it will then be easier to add an
extra gig to replace the 256

Hi,
Actually, I have one 512 MB memory card in already. That is what it came with. I was planning to add one Gig to bring it up to 1.5 Gigs.

Thanks for your reply - I think you are correct in saying that the difference with the mismatched RAM vs dual channel capabilities will be negligible.

Kallum

KMoorehouse Author

Level 1

15 points

May 18, 2007 8:05 AM in response to L0K13

Kallum, the last post brings up a good point. I have
been operating under the impression that you have a
single 512 chip. After reading the last few posts
this morning, I went back and read them all. I
suspect that you indeed have two 256 chips.

I do just have a single 512 MB chip. I am not sure where people were suddenly thinking I had 2 X 256 chips 🙂

Kallum

L0K13

Level 1

0 points

May 18, 2007 8:17 AM in response to KMoorehouse

Good for you then. This could be a bit less expensive in that case. Apple is typically intent on hiding the numbers on their RAM. With a little digging, I have been able to find the original equipment manufacturer in the past (sometimes).

Check Other World Computing (www.macsales.com) - they have a fair amount of info on the site and are well versed in most MAC models should you need phone or email support.

KMoorehouse Author

Level 1

15 points

May 18, 2007 8:20 AM in response to L0K13

To get to the bottom line:

If I add just one more 512 MB chip, will I notice a significant increase in speed and performance ? or do they have to come from the same batch for the dual channel advantage ?

If I add a one Gig chip to the existing one 512 MB already in the machine, will the increase be more than having matched RAM, even if matched RAM gives me dual channel performance ?

Kallum

L0K13

Level 1

0 points

May 18, 2007 8:36 AM in response to KMoorehouse

One more 512 will give you noticable performance boost.

They dont have to be from the same lot. (same manufacturer helps greatly on errors and compatibility issues though)

One 1g chip will likely not give you a faster performance over two 512s. The result of dual channel support is that the free channel is always thinking of the next process needed. So the chips leapfrog one another handling each task faster. If you lose this ability, the system is processing tasks slower even if there is more RAM to do the tasks.

That said, the only reason I would buy a 1gig chip in your case is if you fully intend to get another one as soon as you can afford it. In this way you will ultimately have the dual channel support and in the mean time it will run at pretty much the same performance level as 2 512s.

el-bo

Level 1

19 points

May 18, 2007 9:06 AM in response to L0K13

the reason i thought you may have 2 x 256 is because that's how my macbook is set up

it has 512 memory but this is provided by 2 x 256 blocks

sorry for the confusion

i wonder why they've done it like that..the macbook pro using one block, but the macbooks split across 2....hmmm ????

KMoorehouse Author

Level 1

15 points

May 18, 2007 9:19 AM in response to el-bo

the reason i thought you may have 2 x 256 is because
that's how my macbook is set up

it has 512 memory but this is provided by 2 x 256
blocks

sorry for the confusion

i wonder why they've done it like that..the macbook
pro using one block, but the macbooks split across
2....hmmm ????

No worries.
Regarding the Macbooks - I understand from what I read on the web this morning, that it is important they have to have matched pairs because of the lack of a video card.

The MacBook Pros have the card so it isn't as significant.

Kallum

May 18, 2007 9:21 AM in response to KMoorehouse

Kallum,

Go with an additional 1 GB DIMM, for a total of 1.5 GBs, and don't bother with Dual-Channel support. The benefits of having that additional 512 MBs will far outweigh the speed that Dual-Channel adds.

Scott

KMoorehouse Author

Level 1

15 points

May 18, 2007 10:04 AM in response to Scott Radloff

Kallum,

Go with an additional 1 GB DIMM, for a total of 1.5
GBs, and don't bother with Dual-Channel support. The
benefits of having that additional 512 MBs will far
outweigh the speed that Dual-Channel adds.

Scott

Hi Scott,

Thank you soooooooooooooo much !!!! I really needed this clarification. It has been such a difficult decision as there were varying views.

I thought the extra Gig would have to make a reasonably significant difference and then I can upgrade to two when I can really afford to do so.

Thanks again,

Kallum

Adding mismatched RAM on MacBook Pro ?