New Mac Pro Desktop memory question

Timeline · Post by **Timeline** » Tue Feb 19, 2008 12:17 pm

800MHz DDR2 FB-DIMM ECC 2x4GB

This is the 800mhz memory they put in the new 8 core machines but they also have 1066mhz chips. This would be 20% faster. 7200 series.

We used to do this in the older macs and got allot more speed.
They also have 900mhz sticks.

Anyone know if this would make for a better ram setup?

http://www.crucial.com/store/listparts. ... ro&cat=RAM

Frodo · Post by **Frodo** » Tue Feb 19, 2008 1:44 pm

This is a puzzlement. The machines "come with" 800Mhz blah-blah, but 900/1600 mhz chips are made for it.

This would *imply* that the new machines can make use of chips faster than 800Mhz, but the first important question is to figure out what the RAM bus limit of the machine itself really is.

I can only surmise from this Apple Developer doc that the RAM bus itself is 800Mhz:

http://developer.apple.com/documentatio ... 1200331177

If that's the case, putting in faster RAM would be a waste.

However, there remains the issue of why 900/1600 RAM is being made for the Mac.

This is a question for Crucial which should be corroborated by Apple to sort out under what circumstances the faster RAM could be currently used effectively.

Wish I knew...!

Dave Bourke · Post by **Dave Bourke** » Tue Feb 19, 2008 2:07 pm

Quoted from OWC's current newsletter:

"The new Mac Pros also take new, faster Memory. To compliment the 1600MHz bus, these new models take 800MHz FB-DIMMs. In addition to the higher memory speed, Apple officially supports up to 32GB of memory in these new models as well. You'll save up to 75% by purchasing the extra memory upgrades from us, btw...

"On that note - for maximum memory throughput, Apple does soemthing a little different when you purchase the min 2GB config. Instead of standard pair location - where only 2 modules are installed, one module is placed in each riser to provide maximum memory performance. As soon as you add more memory, you'll need to move that Apple module to be in the appropriate pair location.

"Also interesting... with a Quad x 1 system, you'll get about your max memory throughput once you have 2 or more pairs of any size installed. With a Quad x 2, throughput goes up with more memory and with 2GB x 2 or 4GB x 2 Pairs... 8.0GB via 2 pairs of 4GB actually yields more throughput than 4 x 2GB (1GB x 2) pairs installed. Having more memory available is always better than less, but definitely some optimal configs for memory throughput - at least on an 8-core quad x 2.

"For more information, we've got an installation 'cheat sheet', video, and soon (if not by time you read this) the memory config performance graphs all online here.

Frodo · Post by **Frodo** » Tue Feb 19, 2008 8:38 pm

Dave-- that's very important info (THANKS!)-- and I would think it also a major selling point that could be more easily found in Apple's documentation. Granted-- I didn't snoop as thoroughly as I could have, but in the end it's good news.

So-- the bus IS 1600Mhz (as opposed to topping out at 800 or as my typo indicates, 1066).

You know, I'd go for the max where memory is concerned, but then I have a weakness for all things related to computer memory...

Timeline · Post by **Timeline** » Wed Feb 20, 2008 3:28 am

Then I guess my minimum step should be a pair of 4gb sticks? Should they be the faster 900's or 1066? This is the question as well plus I need to know if you can run mixed speed sticks. I would think not and should the original 800mhz sticks be removed completely?

Dave Bourke · Post by **Dave Bourke** » Wed Feb 20, 2008 3:38 am

OWC know all there is to know about RAM and they don't mention that 900 RAM. Are you sure that it's Apple-certified for the machine in question?

You really should be asking an expert these questions, Timeline. I've always bought my Mac stuff from OWC because I've found them to be knowledgeable, fast, reliable, and excellent value for money. You can webmail your questions here:

http://eshop.macsales.com/Service/sales_request.cfm

Kind regards.

monkey man · Post by **monkey man** » Wed Feb 20, 2008 3:56 am

Frodo wrote:... as opposed to topping out at 800 or as my typo indicates, 1066.

See you on the Hastings... I mean, hustings, Hobby.

RAMBro' wrote:You know, I'd go for the max where memory is concerned, but then I have a weakness for all things related to computer memory...

No kidding, Hobby!

Hey, at least you've taken the first step... admitting there's a problem.

Timeline · Post by **Timeline** » Wed Feb 20, 2008 3:58 am

Dave Bourke wrote:OWC know all there is to know about RAM and they don't mention that 900 RAM. Are you sure that it's Apple-certified for the machine in question?

You really should be asking an expert these questions, Timeline. I've always bought my Mac stuff from OWC because I've found them to be knowledgeable, fast, reliable, and excellent value for money. You can webmail your questions here:

http://eshop.macsales.com/Service/sales_request.cfm

Kind regards.

Your right. I'll do that. Thanks for the links David.

Hi MM. :-----D

monkey man · Post by **monkey man** » Wed Feb 20, 2008 4:06 am

Hey Gary; good to see ya man.

FWIW, I'd do as Dave suggested - many Unicorns have been very happy with OWC for RAM.

Timeline · Post by **Timeline** » Wed Feb 20, 2008 8:33 am

Yea, I think it's a pretty good company too. I just emailed them and asked about the ram buss limits so I'll post what they say.

Cheers
G