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BARE FEATS - real world Mac speed tests

"BARE facts on Mac speed FEATS"
Rob-ART, Main Mad Scientist (aka Dr. Frankenstein)
Bet-TAY, Special Features Edtior (aka Frau Blucher)

MEMORY TESTS, TAKE 2:
"early 2008" Mac Pro 3.2GHz 8-core

Originally posted January 19th, 2008, by rob-ART morgan, mad scientist
Updated February 22nd, 2008, with test results for many more configurations.

It's my custom to order our Mac towers with minimal memory. Apple's memory is of good quality but I feel they charge too much. So I vote with my dollars. I have found reliable alternate sources for Mac Pro memory.

I look for companies that have a reputation for providing strong upgrade support to Mac power users. Two good examples are Trans International and Other World Computing.

With the help of samples of 1GB, 2GB and 4GB FB-DIMMs from both Other World Computing and Trans International, we were able to test 12 different memory configurations using our special 64-bit parallel multi-threaded version of STREAM to see which of those configurations produced the best memory bandwidth.

In the Table below, we averaged the results for the Copy, Scale, Add, and Triad functions of STREAM to produce a single speed rating in gigabytes per second. Test system was an "early 2008" Mac Pro 3.2GHz 8-core system running Mac OS X Leopard 10.5.2.

Configuration
Total Memory
Speed Rating
4 x 1GB
4GB
6.5GB/s
6 x 1GB
6GB
6.7GB/s
2 x 1GB + 2 x 2GB
6GB
6.5GB/s
4 x 2GB
8GB
6.5GB/s
8 x 1GB
8GB
7.5GB/s
2 x 1GB + 4 x 2GB
10GB
6.8GB/s
6 x 1GB + 2 x 2GB
10GB
7.5GB/s
6 x 2GB
12GB
6.8GB/s
4 x 1GB + 4 x 2GB
12GB
7.5GB/s
2 x 1GB + 6 x 2GB
14GB
7.5GB/s
8 x 2GB
16GB
7.5GB/s
4 x 4GB
16GB
7.0GB/s
8 x 4GB
32GB
7.5GB/s

FILL ALL 8 SLOTS, GO FASTER
As you can see from the results posted above, any configuration that filled all 8 memory slots produced the 7.5GB/s average speed. However, the advantage of the 8 slot configurations over the slowest was only 15%. You may feel you can live with that until you can afford to fill all 8 slots.

THE "X" FACTOR
Though some of our configurations involved various size mixtures, we consulted with an engineer knowledgeable about the architecture of the "early 2008" Mac Pro. He suggested two things that may not show up in our benchmarking:
1. The pairs on the top riser (slots 1&2 or slots 3&4) should match the pairs in the bottom riser (slots 1&2 or slots 3&4) in terms of size if you want the maximum benefit to be gained by interleaving in real world applications.
2. The 2GB and 4GB FB-DIMMs are typically Dual-Rank (DR) while the 1GB FB-DIMMs tend to be Single-Rank. Ideally, you want all DR modules.

TEMPERATURE MONITORING
We ran a stress test created by Lloyd Chambers of DigLloyd.com to heat up the memory. It uses all the memory and runs the 8 cores at 100%. During the stress test, the temperature, according to Temperature Monitor, averaged 160 degrees F for both OWC and TransIntl memory. Of course, each module reported a different temperature with the highest being 176 deg F in both cases. No modules came near 190 deg F, at which they supposedly "break a sweat."

HOW MUCH MEMORY IS ENOUGH?
"You can never be too thin, too rich, or have too much memory."

How much memory you need depends on what you do and how you do it. As I write this, I have 10 relatively mundane user apps running on my MacBook Pro (Mail, Safari, Address Book, Calendar, Preview, etc.). Activity Monitor reports 2.67GB in use. I'm glad I have 4GB installed.

We ran the Retouch Artists benchmark action file using 300MB file in Adobe Photoshop CS3. We observed how much memory was gobbled up during the run. It was the only app running, yet, though we specified only 3GB of memory cache, Activity Monitor reported 13+GB in use! What's happening is that Mac OS X Leopard has the ability to hand over unused memory to apps for caching when they use up their 3.5GB allocation limit. (Ditto for Tiger.)

When we render the TotalBenchmark with After Effects CS3 with Multiprocessing enabled, it spawns 8 sub processes on our 8-core system which together grab 13+ GB out of our total of 16GB.

So how much memory should you buy for your Mac Pro? As much as you can afford. We recommend 8GB for most Mac Pro users (8 x 1GB or 4 x 2GB). We have both of our 8-core Mac Pros configured with 16 GB (8 x 2GB). If we could afford it, we'd run 32GB (8 x 4GB) in both.

SPECIAL THANKS TO...
John Poole at Primate Labs (creators of Geekbench) built a special 64-bit and parallel multi-threaded (openmp) version of STREAM 5.8 for us.

RELATED LINKS

Other World Computing used our 64-bit STREAM app to test various memory configurations in 4-core and 8-core 2.8GHz "early 2008" Mac Pros.

Bare Feats' CPU crunch tests on the 3.2GHz Harpertown Mac Pro versus others.

Bare Feats compares the Radeon HD 2600 XT to the optional GeForce 8800 GT.

Bare Feats compares various potential boot drives for the "2008" Mac Pro including the new Samsung SpinPoint F1.

Bare Feats compares the speed of using 667MHz instead of 800MHz in the "early 2008" Mac Pro.

Bare Feats' power usage and noise level testing on the 3.2GHz Harpertown Mac Pro vs the 3.0GHz Clovertown Mac Pro.

Apple Online Store

WHERE TO BUY A MAC PRO
When ordering products from Apple Store USA, please click THIS TEXT LINK or any Apple display ad as your "portal" to the online store. In so doing, you help to support Bare Feats.

(DON'T LIVE in the USA? See links for Apple online stores in other countries.)

Also check with Small Dog Electronics and Power Max. (Power Max takes trade-ins.)

WHERE TO BUY MAC PRO MEMORY
Apple charges and arm and a leg. We recommend ordering your Mac Pro (or MacBook Pro) with the minimum RAM config and the matching set of memory modules from...

Other World Computing or Trans International

MaxUpgrades makes max_flow, a kit to keep your Mac Pro memory running even cooler. They also have a kit called "MaxConnect" which enables you to use the lower optical bay to add four more internal hard drives for a total of eight.

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2008 Rob Art Morgan
"BARE facts on Macintosh speed FEATS"
Email , the webmaster