Photoshop CS3 not seeing 3 GB RAM?

AW
Posted By
Allen_W
Jun 20, 2007
Views
1538
Replies
19
Status
Closed
I just upgraded my WinXP PC to 3 GB RAM. WinXP tells me I have 2.5 GB free, 500 MB used. But Photoshop CS3 preferences says only 1700 MB available RAM. Shouldn’t Photoshop say 3000 MB available RAM? Why is Photoshop saying less? Is something wrong here?

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george_dingwall
Jun 20, 2007
Hi Allen,

I may be wrong here Allen, but I think Photoshop for windows can only see 2GB ram anyway.

It might be deducting the other 300MB from the 2GB because it is seeing that as allocated to windows systems and other memory resident programs.

Just a thought.
BL
Bob Levine
Jun 20, 2007
This has been discussed many times. Search the forum for /3 gig switch.

Note: Don’t even bother if you’re using XP Home.

Bob
AW
Allen_W
Jun 20, 2007
I’m using XP Pro. So I need a switch to run Photoshop with more than 2 GB RAM?
H
Ho
Jun 20, 2007
Actually, with only 3G you should probably just leave it alone.
J
Jim
Jun 20, 2007
wrote in message
I’m using XP Pro. So I need a switch to run Photoshop with more than 2 GB RAM?
You need the /3GB switch to obtain up to 3 GB of virtual address space for any program in Windows. Note that virtual address space and RAM are not the same thing.

There isn’t much point to installing more than 3 GB of RAM.

Jim
AW
Allen_W
Jun 20, 2007
is it better to leave photoshop to use the first 2 GB RAM and let the extra 1 GB be used by other programs? what file sizes will i actually want photoshop to use up to 3 GB ram?
H
Ho
Jun 20, 2007
If you allocate all your RAM to PS, what will your plugins, OS and other apps use? If you want PS to use 3G, buy more RAM.
AW
Allen_W
Jun 20, 2007
its not saying ps uses 3 gb, its how much is listed as available…
DW
D.W.Thompson
Jun 21, 2007
I had the same problem <http://www.adobeforums.com/cgi-bin/webx/.3bc437cb/2> and added the 3gb switch. CS3 now shows 2655mb available and I let it use 1911mb. I’m running XPpro.
KS
Kenneth_Seidman
Jun 21, 2007
" This has been discussed many times. Search the forum for /3 gig switch. Note: Don’t even bother if you’re using XP Home"

There is a common misconception that the /3 GB switch does NOT work with XP Home. This may have been true in early versions? (pre- Service Pack 2?)… Around Feb of this year Microsoft started documenting the use of this switch (and related switches), referring to there use with BOTH XP Home and XP Pro.

I have been happily using the /3 GB switch and the /userva switch on my Dell Dimension 8400, XP HOME, SP2, 4 GB of RAM for about a month now. Based on replies from users in other forums (e.g. DPreview.com) others also use it successfully with XP Home. Photoshop CS3 has 2.6 GB available to it on my system. CS3, and other applications have been completely stable.

As with XP Pro there is no guarantee that the switch will work with an XP Home system, or that it will be stable. If instabilities occur the "fine tuning" /userva= switch can help. It appears to depend on chipset and bios, perhaps other things too.

Sorry to take up so much space replying, but it took me dozens of posts and weeks to find out this information. I hope this helps out someone else.

Ken
AW
Allen_W
Jun 21, 2007
so using the 3 gb can possibly lead to unstable problems?
C
chrisjbirchall
Jun 21, 2007
You need to read Microsoft’s "disclaimer" before throwing the switch.
AW
Allen_W
Jun 21, 2007
does this ‘unable to see 3 gb’ problem only affect photoshop? or are other programs affected as well?
DM
dave_milbut
Jun 21, 2007
by default, apps are only given access to 2 gig in xp.
AW
Allen_W
Jun 21, 2007
each app can use up to 2 gb per app unless i use the switch? is this a 32 bit thing?
J
Jim
Jun 21, 2007
wrote in message
each app can use up to 2 gb per app unless i use the switch? is this a 32 bit thing

No. Every process on the system must map the operating system into its virtual address space so that it can use the many facilities that the operating system furnishes.

For programming convenience, the bounday between that part of the 32 bit address space which is available to user processes and that part of the 32 bit address space which is the operating system lies at the 2GB line. Most virtual operating systems place the boundary at this line because it only takes checkin a single bit to determine whether a virtual address lies in user space or system space.

Once upon a time this division caused no problems because few if any processes needed such a large user space. However, things are different now.

Hence, Microsoft devised a method for allowing up to 3GB of virtual address space for the user programs and thus limiting the operating virtual address space at 1GB.
You enable the method with the /3GB switch.

There is a slight performance penalty associated with the /3GB switch because now the system must check 2 bits to determine where an address lies. In most computer architectures, checking only 1 bit is very quick. It usually takes longer to check 2 bits though.

A program such as PS will test the operation of the /3GB switch quite vigorously because it is so memory intensive.

Jim
H
Ho
Jun 21, 2007
Most apps can’t use the extra RAM. An app that is Large Address Aware (CS2) can make use of it if the switch is employed. The reason I advised against your using it is because CS2 doesn’t actually know how much RAM you have. If you insert the switch in your boot.ini, CS2 will obligingly raise its upper RAM allocation limit by about 1GB. If you don’t use restraint when setting the percentage of RAM in CS2 then you can end up with a system that is less responsive and maybe less stable than you had before you used the switch.
AW
Allen_W
Jun 21, 2007
even though most apps will only use up to 2 gb, the extra 1 gb isn’t wasted right? it can still be used by other apps and windows when running multiple apps?
DM
dave_milbut
Jun 21, 2007
even though most apps will only use up to 2 gb, the extra 1 gb isn’t wasted right? it can still be used by other apps and windows when running multiple apps?

yes.

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