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When you say matched pairs for ram.....

Obsidian6

Obsidian6

macrumors 6502a
Original poster
Apr 29, 2006
683
3
Laguna Niguel, CA
Ok so I want to throw in an extra 1Gb stick into my powerbook to put it at 2GB.

I popped it open and noticed that the ram module is made by transcend, looked up the price, and i wasnt too happy, OWC would be significantly cheaper for me. If i were to get a 1GB stick from OWC, would that create a problem as far as the whole "matched pair" thing goes?

should i just sell the 1.5GB ram that is currently in it and buy 2GB from OWC?
 
First, if you're talking about a PowerBook rather than a MacBook/MacBook Pro, I wasn't aware that matched pairs did a thing for performance one way or the other--that was not a feature of the G4/PowerBook architecture. Somebody please correct me if I'm wrong.

Second, if you ARE talking about a MBP and misspoke, I THINK as long as the RAM is specced the same and of the same module size that it will be treated as a matched pair. I have no objective proof of this other than that the not-perfectly-matched pair in my MPB appears to have low-level memory throughput benchmarks higher than if the memory were operating single-channel, but since I know of no way to actually ask the MacOS whether it's running in dual-channel mode (anybody?), this may be a mistake on my part.

Of course, in the Pro systems where the RAM isn't being shared by the graphics chip, you're talking about a 3% speed increase at best, so it's not like it's something to get worked up over.
 
ahh i see. I didn't know if that actually made a difference or not in the powerbooks. ( yes i am talking about a PB G4, the one that is in my sig )

so even though it uses DDR2 it doesn't matter which "brand" it is, as long as its the same spec?

if so, thats good to hear because that will save me some money :)
 
The last revision of PowerBooks with DDR2 RAM do support dual-channel. The problem is that the level of "matching" required for matched pairs goes beyond the specs that are listed in the documentation. Practically speaking, the only way you can guarantee that your RAM is a matched pair is to buy two identical sticks at the same time. Otherwise it's a gamble...you can try to match specs as closely as you can and then hope for the best, but there's a very good chance they still won't operate as a matched pair.

That said, the performance benefit of matched pairs isn't that high for the PowerBooks, so I wouldn't really worry about it.
 
I know that you are trying to achieve the best performance out of a future RAM upgrade. But as far as I am concerned Pair matching of memory hasn't been a real issue since PC66 with the G1 and G2 PPC machines (mid-90's).

In this modern world I just say look for two things:
1. The Lowest Price
2. Lifetime guarentee
 
well. with that useful bit of information logged into my databanks.

OWC is the best bet for sure.

i'm looking at about $94 for a 1Gb stick with a lifetime warranty. i have no idea what the warranty is like on a transcend stick of RAM, but i imagine it is lifetime as well.

as always, thank you all for answering my never-ending supply of questions!
 
i have one more question.

the ram currently in my powerbook is 533mhz. i see on crucial that they offer modules that are 667mhz.

would these modules work in the powerbook if i were to buy 2gb together?
 
GimmeSlack12 said:
But as far as I am concerned Pair matching of memory hasn't been a real issue since PC66 with the G1 and G2 PPC machines (mid-90's).
Click to expand...
Not 100% true--in the new MacBooks and Mac minis (and I suppose those edu iMacs), since they use shared main memory for the graphics (which has not been the case with any Mac to date), the speed boost from dual channel apparently makes a noticible difference. It would stand to reason.

But since that's not what the poster has, it's not worth getting worked up about.

One question for WildCowboy: I've heard the same thing you're saying about dual channel requiring "REALLY" matched pairs, as opposed to just same-spec modules, and I've heard a few people saying that the Core Duos aren't that picky. I have no technical knowledge one way or the other, but I'm curious where you get this information, just so I can reference it in the future--I like to know what I'm talking about.

For that matter, is there any easy way to check if the memory is being used as dual channel? I believe Windows will tell you one way or another (forget HOW, of course), but is there something I can check without installing BootCamp?
 
AGoglanian said:
i have one more question.

the ram currently in my powerbook is 533mhz. i see on crucial that they offer modules that are 667mhz.

would these modules work in the powerbook if i were to buy 2gb together?
Click to expand...
I would PM CanadaRAM, he knows all about this stuff
 
AGoglanian said:
i have one more question.

the ram currently in my powerbook is 533mhz. i see on crucial that they offer modules that are 667mhz.

would these modules work in the powerbook if i were to buy 2gb together?
Click to expand...
I think it will lower the clock speed to 533MHz, but I couldn't swear by it without the article in front of me.

I'd go for 533MHz though, often cheaper and fastest speed that the PowerBook G4 supported anyway.
 
Makosuke said:
One question for WildCowboy: I've heard the same thing you're saying about dual channel requiring "REALLY" matched pairs, as opposed to just same-spec modules, and I've heard a few people saying that the Core Duos aren't that picky. I have no technical knowledge one way or the other, but I'm curious where you get this information, just so I can reference it in the future--I like to know what I'm talking about.
Click to expand...

To tell you the truth, I don't have any technical knowledge about it either. My most credible source for this info was in fact CanadaRAM, but he's stepped away from the forums, so he's not able to add any additional info on this.
 
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