3 GB Switch Supported by XP Home Edition?

KS
Posted By
Kenneth_Seidman
Apr 24, 2007
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621
Replies
5
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Closed
Can the /3GB switch be used to allocate more RAM to Photoshop (CS or CS3) when using XP Home Edition?

I know this switch can ( but is not guaranteed to) work with XP Pro and I have found numerous posts about its use at this and other sites but it is not clear to me that it won’t work with XP Home also. If you refer to the Microsoft Article 833721 it would seem to imply (to me at least) that the \3GB switch IS supported by XP Home… perhaps it was not in the ‘early days’ of XP?

<http://support.microsoft.com/kb/833721>

Note that the "Applies To:" section at the bottom of the article include XP Home Edition.

I’ve got a Dell Dimension 8400 (935 Chipset) with 2GB of RAM. I would like to have 4 GB if RAM but I don’t want to waste my money if there is no possibility Photoshop will use the extra RAM if I stick with XP Home.

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MD
Michael_D_Sullivan
Apr 25, 2007
No, it doesn’t work with XP Home.
KS
Kenneth_Seidman
Apr 28, 2007
Yes, it does work with XP Home!

I’ve just tried it. A MATLAB application I use has a feature which reports virtual memory that available for it to use. It increases from 2047 MB to 3071 MB when I use the /3 GB switch. (I’ve now got 4 GB or RAM). Also the userva switch works… useful for fine tuning.

I also tried the /3GB switch with Photoshop CS but that application apparently does not have the capability to use the additional address space. I’ll be getting CS3 and I expect the the 3 GB will be available to CS3 (as it is with CS2).
MD
Michael_D_Sullivan
Apr 28, 2007
Well, well, well. I guess the MS site was wrong; it wouldn’t be the first time.
DM
dave_milbut
Apr 29, 2007
cs should report around 2700 with the /3gb switch iirc from what i’ve read here. maybe that’s a limitation of xp home.
KS
Kenneth_Seidman
Apr 29, 2007
I’ve added the additional 2 GB of RAM and have tried the /3GB switch and also the combo: /3GB/userva=2850.
What I’ve found out so far is as follows:

Use an application called MATLAB :
1) 2 GB RAM (and no switches) -> 2047 MB Virtual Memory
2) 4 GB RAM and /3 GB switch -> 3071 MB Virtual Memory
3) 4 GB RAM and both switches-> 2851 MB Virtual Memory

I believe this means the RAM and switches are all working as expected.

Also, my BIOS indicates 4 GB of RAM, and My Computer shows 3.2 GB RAM (which is okay too since it is not all reported)
Here is where it gets wierd:

I am using Photoshop CS, Educational Version. For the above three cases I find (using Photoshop Preferences/Memory)
1) -> 1764 MB available
2) -> 1777 MB available
3) -> 1777 MB available

I was expecting Photoshop to show about 2600 MB available with the switch and extra RAM (see the above post by Dave Milbut)

Furthermore, in case 2 I repeatedly get a disk IO error during a convert to RGB command on a very large file. Case 3 eliminates this problem. Perhaps setting the percentage use below 75% would also.

BUT my question and concern is why Photoshop CS is not getting more virtual memory for case 2 or 3?

Does Photoshop CS (and/or Educational version) Not have the capability to access the extra memory?

…. I think CS is the problem (not XP Home). Looking through the Adobe "TechNotes" e.g: "Optimize Performance of Photoshop CS3 on Windows XP and Vista". I found mention of the 3 GB switch in this CS3 TechNote and also in the CS2 version but NO mention anywhere in the CS version.

I’ll be upgrading to CS3 in a few weeks so this isn’t a big concern, but can anyone else verify the 3 GB switch (i.e extra virtual memory) is not supported by CS (vs. CS2 and CS3)?

Thanks,
Ken

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