[calverson]

Anyone tried more than 4GB in the MacBook Pro? Apparently, you can get 6GB kits, but technically any RAM that meets the specs should work. Also, would you need Snow Leopard to make it work nice?

[Charles Bouldin]

Originally Posted by calverson 

Anyone tried more than 4GB in the MacBook Pro? Apparently, you can get 6GB kits, but technically any RAM that meets the specs should work. Also, would you need Snow Leopard to make it work nice?

Works like a charm. I have a 4+2 gig configuration in my March 2008 Santa Rose MBP. No problems, just a whole lotta ram. Activity monitor shows, over the past week or so, about 2.5 gigs of pageins, 468 kilobytes of pageouts, ie, basically none. I don't run anything huge, but I run many apps simultaneously.

I bought the 4 gig module from Newegg for about $160. DDR2 is considerably cheaper than DDR3.

[jjs357]

I also just installed the 4GB module from Newegg in my new 17 in MacBook Pro and can confirm that it works for me -- all 6GB are being used. Nice to bring up Fusion and leave all of my browsers and developer tools open at the same time and experience no swap-outs. I had waited for the Powerbook refresh hoping for 8 GB capacity. The 17 in did not get a case update but the 320 GB disk is nice and with the extra memory it is almost as good as the new 15 in edition. I expect that a future OS update might allow 8GB usable and if so I can swap out the 2GB I left installed for another 4GB.

I am enjoying the glossy screen too.

[Simon]

Several RAM resellers are now offering 6 GB kits for both the unibody MBPs and the Crestline MBPs. They are advertising them as fully supported with addressing and use of all 6 GB. These are resellers with no questions asked refund policies. So obviously these kits will work in these Macs.

We have a unibody MBP here at work that we fitted with 6 GB RAM and it works just like it should. All 6 GB are addressed, all 6 GB can be gobbled up by apps and are also properly released when the apps terminates. We have yet to try it with a Crestline MBP. Unfortunately we can't just swap the 6GB from the unibody to the Crestline (DDR3 vs. DDR2). We aren't expecting it not to work on the Crestline, but there seem to be certain DIMMs that have caused people problems and I'd like to look closer into this. I guess it has to do with timings/SPD issues.

[Brien]

Didn't Barefeats find there wasn't any noticeable gain from 4gb to 6gb?

[Simon]

Originally Posted by Brien 

Didn't Barefeats find there wasn't any noticeable gain from 4gb to 6gb?

BareFeats tested the unibody MBP with 6 GB and 4 GB. The goal was to find out if unmatched DIMMs would lead to a considerable performance decrease. What they found was that it didn't.

But of course if somebody has 4 GB and is paging out to disk he/she should get 6 GB immediately. Paging out to disk makes memory i/o orders of magnitude slower. Not 0.8% like the unmatched DIMMs, but something around a factor 1000. Obviously if 4 GB are enough you don't need to go unmatched. But if you page out at 4 GB, there is absolutely no reason not to go to 6 GB.

"The 6GB configuration produced essentially identical benchmark results to the 4GB configuration in our 2.8GHz MacBook Pro. The difference ranged from -.5% to +1.7% or an average difference of +.28% or less than 1/3 of one percent. I call that negligible. Or, in other words, you should have no worries about a speed penalty imposed by non-matching memory modules and loss of interleaving.
And when you consider the 6GB configuration potentially means less virtual memory swaps, then the only consideration is the cost. Maybe instead of ordering your MBP with the $500 128GB SSD, you should save your money for a 4GB memory module.
Looks like a winning combination to me. You can never be too thin, too rich, or have too much memory."