Upgrades: How Much Memory?

Your Mac's CPU cannot run faster than its rated speed, but you can minimize idle time with enough memory. With too little memory, your Mac has to use the disk, so everything slows down:

• Your Mac has to constantly swap between the memory chips and the drive ("virtual memory"). As a result, your Mac crawls.
• With “extra” memory, your Mac can keep programs and files in memory ("caching"). Quit and relaunch a program? Watch it start in a fraction of the time! Or, keep all your programs open at once.

Simple rule—

Always install 8GB or more memory; it’s a small cost relative to the Mac itself.

Job size — enough is enough (memory)

Monitor your memory usage.

All simultaneous activities make demands on available memory:

• Mac OS X itself consumes a good chunk of memory. Figure 1GB overhead for OS X itself.
• Figure 1GB free memory to avoid speed problems.
• Each running program takes memory;
• Some programs require large amounts of memory to work efficiently (Photoshop).
• Some programs have peak surges of memory use that come and go quickly when there is enough memory, but cause massive slowdown without enough.
• Look to have at least 2GB free to avoid frustration during peak usage.

Memory sources

Click to view recommended memory

I don’t fool around with bargain basement memory— I want high quality at a affordable price.

Read my thoughts in Memory Upgrades — How Does Your Vendor Test?. The antics of some vendors are disturbing; I’ve seen some vendors announce “compatible” memory well before production Macs are available; they can’t possible have tested final production machines.

No vendor has 100% fail-safe memory, so you might want to test your entire system reliability using diglloydTools MemoryTester.

But if you’re upgrading an entire system, you might want it all done in one job, so check into an MPG Pro Laptop and/or an MPG Pro Workstation.