MacBook's "NEED" matching RAM sticks?

[Abstract]

Hi,

I know it's "highly recommended" that I buy RAM in matching pairs. Many people give this advice, but I find that they don't know exactly why. Admittedly, I don't either.

I have 2 x 512MB sticks of RAM (ordered it from Apple with my MacBook since it was actually cheaper to do it this way in Australia) and my machine chokes on such a small amount since I play with lots of photos. My old 12" PB only had 1.25 GB total, and it seemed to run fine, so I guess this need for RAM is a consequence of the new architecture or something. (I have around 500,000 page-outs in 11 days of uptime)

I want to buy a 1GB stick of RAM, but don't have enough money for 2 x 1GB sticks. If I buy it, I'll have 1x 512MB stick, and a 1GB stick of RAM, for a total of 1.5 GB. I believe that the speed of my RAM will be slower if I have a mismatching pair installed, but will my machine still benefit from the increase? Will it run as if it only had 1.2-1.3 GB of RAM because of the resulting slowdown of my RAM performance?



PS: I've done 3 searches of the entire board before starting this thread.

 

[topgunn]

Matched RAM Guide

The last bit answers your question best:

upgrading a 2 x 256MB system to 1 x 256 MB + 1 x 1 GB would be wiser than upgrading it to 2 x 512 MB for almost all users

 

[mad jew]

In other words, you'll benefit more from increasing your total RAM to 1.5GB rather than cruising along on a matched 1GB.

 

[count chocula]

i looked on the support pages on apple's website and it appears that umatched will work, but having matched pairs takes advantage of dual channel so that is what they recommend. as far as 1.25gb unmatched vs. 1gb matched, i have no idea what will be better.

 

[Sun Baked]

Basically Apple says ...

"SO-DIMMs must be the same size and type for the interleaving function to be used to improve performance."

But then again, more memory that doesn't enable interleaving, would still perform better than not enough interleaved memory.

---

Remember a HD operates at around 50MB/sec, compare that to the speed of the DIMM and you will see a vast difference (aka vs 5300MB/sec of real RAM.)

When you double the speed of RAM you are gaining fractions of a second, when you slow down to HD speed because you don't have enough memory -- you add seconds and a spinning rainbow.

More memory is typically a huge performance boost, when you add enough to take the HD out of the equation. Once you start playing with interleaved vs. non-interleaved -- it's generally not as huge a boost in general use as HD vs. RAM.

 

[JurgenWigg]

It was explained to me like this:

If you only have a 1 gb stick in there, you can look at tons of photos and stuff, but it won't be so great to do that and check your email, make a webpage, write a paper at the same time because it's all running off of that one stick.

If you go with 2x 1 gb, it's using two sticks and they won't be each working as hard. With mismatched pairs, it's no crime or anything, but the multi-tasking and individual preformance of programs will vary a bit, but the ceiling will definately be higher.

Go for it and get the other stick when you can, you'll lose the benefit of the dual channel for now, but it'll still be better.

 

[Abstract]

Thanks to all.

I'm likely to get the 1GB stick and just sell the 512 MB stick on eBay or something.

 

[66217]

Does it affects if you have a 256mb from Apple and one of 1Gb from another brand?

 

[lil chris]

Not if it's decent stuff. If you start cutting corners buying cheap RAM, the OS will be picky about it.

 

[danny_w]

I believe that the main reason that Apple strongly recommends matched pairs for the Macbook (but not the Pro) is because of the integrated graphics. You can buy a MBP with only one stick and an empty slot, but they don't even offer the MB this way (matched pairs only). I don't know how much effect it actually has, just that this is the way that Apple explains it. I would imagine that it wouldn't make much difference for non-graphics intensive stuff.