All Posts by Date or last 15, 30, 90 or 180 days.
also by Lloyd: photography and
Thank you for purchasing through links and ads on this site.
diglloyd B&H Deal Finder...
Buy other stuff at
Memory Upgrades for 2019 Mac Pro - Save Up to 65% vs Factory Costs
Today’s Deal Zone Items... Handpicked deals...
$799 $499
SAVE $300

$449 $379
SAVE $70

$1000 $850
SAVE $150

$799 $299
SAVE $500

$249 $234
SAVE $15

$290 $250
SAVE $40

$1149 $799
SAVE $350

$1199 $999
SAVE $200

$1299 $1099
SAVE $200

$2799 $2449
SAVE $350

$3899 $3899
SAVE $click

$18599 $17099
SAVE $1500

$369 $239
SAVE $130

$1499 $999
SAVE $500

$764 $399
SAVE $365

$600 $450
SAVE $150

$1499 $629
SAVE $870

$1499 $629
SAVE $870

$7995 $7495
SAVE $500

$420 $170
SAVE $250

$700 $700
SAVE $click

$2999 $2399
SAVE $600

$1699 $1399
SAVE $300

$169 $99
SAVE $70

$1498 $998
SAVE $500

$200 $150
SAVE $50

$370 $300
SAVE $70

$999 $949
SAVE $50

$1099 $999
SAVE $100

$580 $340
SAVE $240

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 16GB Memory Modules for 2009/2010 Mac Pro — 48GB / 96GB in Mac Pro

OWC 128GB memory for 12-core Mac Pro

The revised (Jan 2012) OWC 16GB memory modules now run at full speed of 1333 MHz and one can also mix 16GB and 8GB memory modules (“Dual-Rank 16GB ECC 240 Pin DDR3”).

According to OWC—

These modules do allow full 1333Mhz bus performance and are faster in both 1066MHz and 1333Mhz memory bus Mac Pros with the Dual-Rank design than the Quad-Rank module options they replace.

A 12-core Mac Pro can take 96GB total with six (6) modules. More than that DOES NOT WORK— the Mac Pro will show 128GB installed, but only 96GB is accessible.

I attribute the 96GB limitation to system software issues (bug?), not a hardware limitation. OWC tells me that a Windows boot can address 128GB on the same Mac Pro, so this is clearly a Mac OS X BUG.

Memory beyond 96GB cannot be addressed in Mac OS X Lion (tested)

Using 64-bit MemoryTester, the alloc command can allocate about 91GB of that 96GB before severe virtual memory paging begins. So the absolute limit to addressable memory for a single program about 91GB.

Cut those figures in half for a 4/6-core Mac Pro which can take 3 X 16GB memory modules: about 43-44GB of 48GB.

Adequate memory is crucial for really big files in Photoshop CS5, video processing, etc.

Mix and match

Since the OWC 16GB and 8GB modules can be freely intermixed.

For example, existing 4/6-core Mac Pro users with 3 X 8GB (24GB) could add a 16G module to go to 40GB

Or 12-core users with 6 X 8GB modules could add two 16GB modules to go to 80GB, thus preserving the investment in existing 8GB modules.


Optimal setup for maximum memory bandwidth remains triple-channel memory configuration:

  • 3 modules (not 4) in the 4/6-core Mac Pro (fill 3 of 4 slots).
  • 6 modules in the 8/12-core Mac Pro (fill 6 of 8 slots).

However, the real-world impact of triple channel vs dual channel memory bandwidth is very small, so this can be safely ignored for practical purposes, and if the additional memory is actually needed, then more is far faster.

Max usable memory in 8/12-core Mac Pro is 96GB as 6 X 16GB

Example in my 12-core 3.33GHz Mac Pro

Shown below is one memory configuration in my 12-core 3.33 GHz Mac Pro.

While 128GB is recognized by the hardware, Mac OS X Lion will only use 96GB.

Evidently, Apple engineers don’t test for large memory configurations. This would not be the first reporting bug I’ve seen in Activity Monitor.

128GB will show up, but only 96GB is actually usable.
OWC Accelsior 4M2 PCIe SSD
6000 MB/sec!
Mac or PC.

Ideal for Lightroom, Photoshop, video.
Capacity up to 16TB!
Save Big $$$$ on Memory for 2019 Mac Pro

Up to 65% better pricing than Apple

Lloyd recommends 32GB RDIMM modules for most users (more expensive LRDIMMS are for 512GB or more).

OWC Thunderblade Thunderbolt 3 SSD

Blazing fast, up to 16TB.


√ No more slow and noisy hard drives!

Deals Updated Daily at B&H Photo
View all handpicked deals...

QNAP TS-253Be 2-Bay NAS Enclosure
$449 $379
SAVE $70 | 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__