Memory Makes the Photoshop CS5 Scratch Drive Irrelevant
With the advent of 64-bit Photoshop CS5 for Mac, performance is simple—
Install 24GB memory for set-and-forget, or 16GB on systems for which that is the limit.
See discussion on the Photoshop CS5 Memory Use setting.
How much memory is enough?
Enough is when:
- There is no virtual memory paging;
- Photoshop does not need to write to the scratch volume; it can keep everything in memory.
- The system still has several gigabytes of memory for drive caching.
- Other needed programs can be run at the same time with the above still true.
Few users need more than 24GB, and for many users, 16GB is enough.
Recommendation for 4/6-core Mac Pro
The 4-core and 6-core Mac Pro can take up to 32GB as four 8GB modules in four memory slots.
But CPU performance is 2-3% faster with three (3) modules, which is 12GB or 24GB. Go to 16GB or 32GB only if needed.
Recommendation for 8/12-core Mac Pro
The 8-core and 12-core Mac Pro can take up to 64GB as eight 8GB modules in eight memory slots.
But CPU performance is 2-3% faster with six (6) modules, which is 24GB or 48GB. Go to 32GB or 64GB only if needed.