Is Photoshop on OSX coded to utilize more than 2 GB of memory?

[Jeff]

Can photoshop on Mac OSX utilize more than 2 GB of RAM for a single instance of photoshop?

 

[lina]

Unfortunately, no. Photoshop is still stuck in a 2 GB world

Here's the amount of RAM (per the Pshop Memory Use prefernce panel) shown on this system after a clean boot (can vary depending on what addons are running/installed in OS X. Also varies a bit after running the script, even after the image is closed)

* 512MB RAM - 50% setting = 222MB
* 512MB RAM - 90% setting = 399MB
* 1.5GB RAM - 50% setting = 686MB
* 1.5GB RAM - 90% setting = 1235MB
* 2.0GB RAM - 50% setting = 934MB
* 2.0GB RAM - 90% setting = 1643MB
* 4.0GB RAM - 100% setting = 1807MB
* 8.0GB RAM - 100% setting = 1678MB

Again the reason the max RAM shown in PhotoShop's preference panel is less with 8GB installed than with 4GB is probably due to the OS using a larger cache with more RAM installed, but it would be nice if you could at least use/select all 2GB when you have much more RAM installed. Even PShop's limit of recognizing 2GB (max) of RAM, there is a benefit to having more than 2GB of RAM in the system - at least if you work with larger images and/or run more than one application at a time.

http://www.xlr8yourmac.com/G5/8GB_RAM_Tests/G5_8GB_ram_tests.html

 

[lina]

The soon upcoming Photoshop CS4 will be available in a 64-bit version for Windows Vista 64-bit that will allow huge amounts of RAM to be utilized for very large images, posters, panoramas, etc (but windows-only at this point, possibly the first time the windows version has been developed ahead of the mac version)

With the 32-bit version you'll still see less than 2 GB used (unless the /3GB switch is flipped in the host windows OS - but I have not myself done that.)