2 Rules in Installing RAM on your Mac Pro

I'd like to suggest 2 rules in installing RAM on your 8-Core/10-Core Mac Pro 2009/2010.
8 slots are available in these models: 4 in the front, 4 in the back.

Rule #1: Make slots 1-4 and 5-8 of identical set-up.
Rule #2: Put three memory modules of the same capacity and speed in slots 1-4 and 5-8 (i.e., to operate in triple-channel mode).


"Rule #1" precedes "Rule #2". You don't have to follow these rules in order for it to run. Following these rules will only help you optimize the speed.

Here is an example of when you have 6 x 1GB modules installed:

Installing 2 x 4GB modules

Front: 3 x 1GB + 1 x 4GB
Back: 3 x 1GB + 1 x 4GB
Total: 14GB
Works fine. Follows both rules.

Installing 3 x 4GB modules

Front: 2 x 1GB + 2 x 4GB
Back: 3 x 1GB + 1 x 4GB
Total: 17GB
Will work, but won't be that great. Both rules are not fulfilled.

Installing 4 x 4GB modules

Hmm...maybe I should install it this way to operate in triple-channel...
Front: 3 x 4GB + 1 x 1GB
Back: 3 x 1GB + 1 x 4GB
Total: 20GB
Wrong. Rule #1 precedes Rule #2, so it runs faster this way:
Front: 2 x 1GB + 2 x 4GB
Back: 2 x 1GB + 2 x 4GB
This fulfills Rule #1 but doesn't fulfill Rule #2. It's an average upgrade.

Installing 6 x 4GB modules

Front: 1 x 1GB + 3 x 4GB
Back: 1 x 1GB + 3 x 4GB
This is a great way to install your RAM.

Installing 8 x 4GB modules

Front: 4 x 4GB
Back: 4 x 4GB
This is the best way to install your RAM.

I hope this serves as a reference for your RAM upgrades in your Mac Pro 2009/2010.

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