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Peter Stevens · Jun 21, 2005, 12:54 PM

Hi All,

Another query for any Photoshop users out there or indeed anyone who may be able to assist me.

I've have recently had the luxury of installing the full 8Gb of RAM in my G5 PowerMac Dual 2.0GHz. It's the 'older' model with 8 RAM slots and I've also recently installed Photoshop CS2, not as part of the Creative Suite, but as a standalone application.

In Photoshop>Preferences>Memory & Image Cache, memory usage can be allocated for Photoshop as a percentage of the Available RAM. My problem is that although I have 8Gb RAM installed on this machine, the 'Available RAM' is showing as only 3072Mb. By allocating 90% to Photoshop this gives me a total of 2764Mb for Photoshop.

Could anyone tell me whether this is what is actually happening i.e. nearly 5Gb of unused RAM or is it a 'display' problem where Photoshop doesn't recognise more than 3Gb, but uses it if available ? What I need to avoid, especially when working with very large layered files, is writing to one of the scratch discs rather than using RAM.

Any assistance would be greatly appreciated, or even if I someone can identify whether it's an Apple OS problem or Adobe's problem or if the problem lies somewhere else.

I'm running OS X 10.3.9.....

Thanks,

Pete,
London

jamil5454 · Jun 21, 2005, 01:15 PM

Are you sure OS X is recognizing all your RAM?

Goldfinger · Jun 21, 2005, 01:15 PM

Photoshop does not support 8GB of RAM. Only goes to 4GB, and it doesn't see all of that 4GB either. I have 1GB or RAM in my PowerBook and it only shows around 970MB as available.

Peter Stevens · Jun 21, 2005, 03:37 PM

Yeah, all the RAM is recognised in the System Profiler and listed correctly. It's been checked with the Apple Hardware Test (Quick Test) too and is fine.

Thanks for the replies.

CatOne · Jun 21, 2005, 04:43 PM

Originally Posted by Peter Stevens

Hi All,

Another query for any Photoshop users out there or indeed anyone who may be able to assist me.

I've have recently had the luxury of installing the full 8Gb of RAM in my G5 PowerMac Dual 2.0GHz. It's the 'older' model with 8 RAM slots and I've also recently installed Photoshop CS2, not as part of the Creative Suite, but as a standalone application.

In Photoshop>Preferences>Memory & Image Cache, memory usage can be allocated for Photoshop as a percentage of the Available RAM. My problem is that although I have 8Gb RAM installed on this machine, the 'Available RAM' is showing as only 3072Mb. By allocating 90% to Photoshop this gives me a total of 2764Mb for Photoshop.

Could anyone tell me whether this is what is actually happening i.e. nearly 5Gb of unused RAM or is it a 'display' problem where Photoshop doesn't recognise more than 3Gb, but uses it if available ? What I need to avoid, especially when working with very large layered files, is writing to one of the scratch discs rather than using RAM.

Any assistance would be greatly appreciated, or even if I someone can identify whether it's an Apple OS problem or Adobe's problem or if the problem lies somewhere else.

I'm running OS X 10.3.9.....

Thanks,

Pete,
London

There's a limit of 2 GB per process in OS X 10.3. Tiger bumps this up significantly, but only for specific kinds of processes -- those without a GUI. The GUI libraries are not 64-bit enabled.

As such, you're not going to be able to get a whole lot more RAM specifically for Photoshop. They may be doing some tricks, and if so the absolute maximum you'll be able to access will be 2-3 GB.

This doesn't explain why the OS is only seeing 3 GB... it should see 8... but any single process is really capped at 2 GB of available heap space. A 32 bit machine can use 4 GB pointers, but the application only can grab about 2 GB of this, due to the OS reserving a lot of it.

ChrisF · Jun 21, 2005, 06:50 PM

Originally Posted by Peter Stevens

In Photoshop>Preferences>Memory & Image Cache, memory usage can be allocated for Photoshop as a percentage of the Available RAM. My problem is that although I have 8Gb RAM installed on this machine, the 'Available RAM' is showing as only 3072Mb. By allocating 90% to Photoshop this gives me a total of 2764Mb for Photoshop.

Photoshop CS2 will use up to approx. 3.5GB of RAM total. I can't begin to explain the details but on a machine with 8GB installed, there's no reason not to allocate 100% to Photoshop- it'll never be more than that 3.5GB. Works fine and CS2 is much faster working with files that fit within that space but didn't fit inside of the CS 1 RAM limit.

Goldfinger · Jun 22, 2005, 09:30 AM

Originally Posted by CatOne

This doesn't explain why the OS is only seeing 3 GB... it should see 8... but any single process is really capped at 2 GB of available heap space. A 32 bit machine can use 4 GB pointers, but the application only can grab about 2 GB of this, due to the OS reserving a lot of it.

His OS sees the 8GB, it's Photoshop that doesn't see the 8GB (you can edit the memory use in the photoshop preferences). So, like I said before, Photoshop does not support the 8GB of RAM.

CatOne · Jun 22, 2005, 10:27 AM

Originally Posted by Goldfinger

His OS sees the 8GB, it's Photoshop that doesn't see the 8GB (you can edit the memory use in the photoshop preferences). So, like I said before, Photoshop does not support the 8GB of RAM.

I'm not sure that's the case, due to the fact that he states this:

" My problem is that although I have 8Gb RAM installed on this machine, the 'Available RAM' is showing as only 3072Mb. By allocating 90% to Photoshop this gives me a total of 2764Mb for Photoshop."

I don't know if he's reading "Available RAM" from the "About this Mac" box in the finder -- if so, then something is definitely strange.

But correct, Photoshop cannot use the 8 GB of RAM. There isn't really anything Photoshop can do about this, currently -- a number of system libraries that Photoshop uses are 32 bit (even in Tiger). which means the process that calls them will have a 32 bit address space, which is theoretically capped at 4 GB, but practially capped at a number less than this. 2.7 GB sounds close to the max for me -- 3.5 GB no way.

Goldfinger · Jun 22, 2005, 02:21 PM

Originally Posted by CatOne

My problem is that although I have 8Gb RAM installed on this machine, the 'Available RAM' is showing as only 3072Mb. By allocating 90% to Photoshop this gives me a total of 2764Mb for Photoshop."

I don't know if he's reading "Available RAM" from the "About this Mac" box in the finder -- if so, then something is definitely strange..

He's talking about the "Available RAM" you see in the Photoshop preferences. If you read the post right above your first one you will see the following:

Originally Posted by Peter Stevens

Yeah, all the RAM is recognised in the System Profiler and listed correctly. It's been checked with the Apple Hardware Test (Quick Test) too and is fine.

You see ?

ChrisF · Jun 22, 2005, 02:36 PM

Rather than bicker about this, would it not make more sense to refer to Adobe?
http://www.adobe.com/support/techdocs/320005.html

Peter Stevens · Jun 23, 2005, 03:17 AM

Thanks everyone.

Just to clarify...the OS (10.3.9) sees all the memory in the system profiler. The memory has been checked with the Apple Hardware Test 2.1 (the Quick Test part) and is fine.

In Photoshop>Preferences>Memory & Image Cache the 'Available RAM' is 3072Mb. I have allocated the full 100% as 'Maximum Used By Photoshop' and it runs fine.

Hope this clears things up !

It just leaves me feeling that I've loaded the RAM slots to 8Gb pointlessly. Are there any apps which can fully utilise 8Gb RAM ?

Thanks,

Pete,
London.

Randman · Jun 23, 2005, 03:29 AM

Video.

Or games.

Goldfinger · Jun 23, 2005, 04:22 AM

Originally Posted by Randman

Video.

Or games.

I doubt there are any games that support 8GBs..

ChrisF · Jun 23, 2005, 07:20 AM

Originally Posted by Peter Stevens

It just leaves me feeling that I've loaded the RAM slots to 8Gb pointlessly. Are there any apps which can fully utilise 8Gb RAM ?

If you only run Photoshop, then yes you did make a pointless upgrade. The advantage of 8 GB is that you can assign a bunch of RAM for Photoshop and run your other apps without crippling any of them with a RAM shortage.

CatOne · Jun 23, 2005, 11:01 AM

Originally Posted by Peter Stevens

It just leaves me feeling that I've loaded the RAM slots to 8Gb pointlessly. Are there any apps which can fully utilise 8Gb RAM ?

Not on Panther, no.

On Tiger, a non-GUI process can allocate > 8 GB of RAM. This would typically be a scientific application, forked from a main process to crunch extremely large data sets.

The benefit of having 8 GB of RAM is that you can run Photoshop and a number of other applications at the same time, and have plenty of RAM so nothing is ever paging. Still, 4 GB may have been enough.

Peter Stevens · Jun 24, 2005, 02:28 AM

Thanks to everyone for the help. As a professional photographer the main reason for loading the RAM was to maximise batch processing speed of large numbers of RAW files. For 16-bit NEF/TIFFs, individual image files are 70Mb+. The only other apps running at the same time would be iView Media Pro.

Does anyone feel that at some point during the lifespan of this machine, a PowerMac G5 2.0GHz DP (another two to three years, realistically) that a GUI app will be able to utilise the full amount of RAM ?

I'm also cautious about installing Tiger at the moment. I have it installed (10.4.1) on my older PowerMac G4 500MHz DP machine....testing PS CS2 periodically. Is there anyone with experience of Photoshop CS2/Adobe Camera RAW v3.1 running on Tiger 10.4.1 and are there any problems ?

With all this number-crunching potential on tap perhaps I should offer my services to SETI in downtime.....Just a thought....

Cheers,

Pete,
London.