Thank you for buying via links and ads on this site,
which earn me advertising fees or commissions.
As an Amazon Associate I earn from qualifying purchases.

Other World Computing...
B&H Photo...
Amazon
As an Amazon Associate I earn from qualifying purchases.
877-865-7002
Today’s Deal Zone Items... Handpicked deals...
$180 $100
SAVE $80

$699 $479
SAVE $220

$4900 $3000
SAVE $1900

$2299 $1799
SAVE $500

$1798 $1598
SAVE $200

$3508 $2998
SAVE $510

$1099 $999
SAVE $100

$1099 $999
SAVE $100

$2797 $2497
SAVE $300

$1499 $1349
SAVE $150

$1499 $1299
SAVE $200

$2598 $2398
SAVE $200

$3998 $2998
SAVE $1000

$3498 $2998
SAVE $500

$1199 $1099
SAVE $100

$240 $175
SAVE $65

$1499 $1349
SAVE $150

$2799 $2499
SAVE $300

$7999 $6999
SAVE $1000

$250 $210
SAVE $40

$1199 $1099
SAVE $100

$799 $599
SAVE $200

$999 $949
SAVE $50

$1999 $1449
SAVE $550

$2799 $2499
SAVE $300

$449 $389
SAVE $60

$400 $300
SAVE $100

$1699 $999
SAVE $700

Upgrade the memory of your 2020 iMac up to 128GB

Mac Pro Westmere Real World Memory Bandwidth

2010-08-21 updated 2010-09-05 - Send Feedback
Related: bandwidth, Mac Pro, Macs, memory, memory bandwidth

See test machine configuration.

The memory bandwidth test uses MemoryTester, the numbers are from the stress command. The 'stress' command uses all virtual cores at once for 100% CPU utilization. It is a pure memory-speed-bound test.

Theoretical benefits

The MemoryTester number is a true measure of the ability of a real program to utilize the memory system. Small differences should be ignored as there is some fractional measurement error.

  • Though 1333MHz memory should offer 25% more bandwidth to a real program, testing shows that the gain is only 10% for a real program.
  • Using 1066Mhz memory in the 2010 3.33GHz Mac Pro (1333MHz is stipulated) results in identical memory speed to the 2009 3.33GHz Mac Pro.
  • An 8-core or 12-core system has dual banks of memory, hence greater bandwidth.

Yes, you can use one (1) 8GB module in the hexacore Mac Pro, but the memory bandwidth is severely reduced. Not recommended, but two modules OK.

Click to view a larger graph.

Memory bandwidth as measured by MemoryTester 'stress' command

Does it matter for real tasks?!

Memory bandwidth differences are hard to measure with real program doing real tasks because the on-chip caches mask the effects, and most programs are not memory-access intensive.

To find out if memory bandwidth would actually matter for common tasks, including memory intensive ones, such as Photoshop. I chose the diglloydSpeed1 benchmark, and tested with 2/3/4 modules in the 3.33GHz 6-core Mac Pro. This test has plenty of memory even with 2 modules, so the amount of memory is not a factor.

  • The test took 2.7% longer with two modules as compared with three.
  • The test took 2.4% longer with four modules as compared with three.
  • I also tested with Helicon Focus and Photozoom Pro. No difference between 2 or 3 modules.

If you want maximum speed, stick with three modules. But remember, if memory runs low, more memory is far faster than too little and these small differences seen here are irrelevant.

diglloydSpeed1 using 2 X 8GB or 3 X 8GB

 

OWC Envoy Pro EX SSD
Blazingly fast Thunderbolt 3 SSD!

Up to 4TB capacity, USB-C compatible.

USB-C model also available


Great for travel or for desktop!
OWC Accelsior 4M2 PCIe SSD
6000 MB/sec!
Mac or PC.


Ideal for Lightroom, Photoshop, video.
Capacity up to 16TB!
OWC Envoy Pro Elektron

Ultra-high performance across entire capacity, outperforms the competition.

Tiny, bus-powered, rugged, compact!


√ No more slow and noisy hard drives!
OWC Thunderblade Thunderbolt 3 SSD

Blazing fast, up to 16TB.

YEE HAH!



√ No more slow and noisy hard drives!
View all handpicked deals...

Venus Optics Laowa 105mm f/2 Smooth Trans Focus Lens for Sony E
$699 $479
SAVE $220

diglloyd.com | Terms of Use | PRIVACY POLICY
Contact | About Lloyd Chambers | Consulting | Photo Tours
Mailing Lists | RSS Feeds | Twitter
Copyright © 2020 diglloyd Inc, all rights reserved.
Display info: __RETINA_INFO_STATUS__