Is 8GB or RAM enough to eliminate the need for a scratch disk using Photoshop Elements?

Assume I don't have any other heavy applications running, and at most I'm stiching 4 or 5 5D RAW images.

It's my understanding Photoshop uses RAM first. If there isn't enough RAM it will use a scratch disk for temporary storage space. With the low price of RAM these days it makes it very attractive to use RAM instead of a scratch drive.

I've heard you need between 3x - 5x the largest file size you are using.

You could take a look at how large a scratch file Photoshop is currently using for your typical workflow. Add to that the amount of physical RAM that you have allocated to Photoshop, and that should give you a good idea of how much physical RAM you would need to not be working from the scratch disk.

Also, keep in mind that unless you're running a 64-bit OS (Mac, XP-64, Vista-64), or running Enterprise Server (either 2003 or 2008 version), you can't address more than 4GB of RAM. The additional 4GB wouldn't be recognized by Windows.

I'm running Vista 32 bit with 4 GB RAM but Photoshop CS3 sees less than 2GB. Is this normal do you think?

I'm running a Mac Pro with the latest OS.

For an answer you can check your PS's "efficiency" and also Mac's "Activity Monitor." Add up both the "Free Ram" and the "InActive Ram" (which is available too).

I have 9 Gb and run both CS3 (3 Gb) and Bridge (up to 3GB I have seen it use 1.5) plus 1.5Gb for a Virtual PC and I have never run out. So I believe that you are safe with 8.

How much RAM you need for photoshop depends more on how you set up photoshop than file size. If you have few history states and work with large files with few layers, 2GB may be enough. If you work with many history states and smaller multilayered files then that can eat up RAM faster. So a sensible ~100 history states does require a lot of RAM. For your files, definitely.

Also check out the best way to set up 8GB of RAM. If its 2GB sticks then make sure they are split up, 2 per riser. If its 1GB, well then only one way to do that. If its 4 1GB and 2 2GB I'm pretty sure its best to have all the 1GB together....been a while since I saw that chart.

DIS Ottawa wrote:
I'm running Vista 32 bit with 4 GB RAM but Photoshop CS3 sees less than 2GB. Is this normal do you think?


a 32 bit operating system can only see so much ram. I doubt it will be able to use all of your 4gigs.

google it

DIS Ottawa,

Yes, this is normal. You need to force Windows to allow applications to use up to 3GB of RAM. In XP, this is done by adding the /3GB switch in the boot.ini file. With Vista, you need to use BCDEdit to add the increaseuserva switch and set it to 3 GB. This will allow applications such as Photoshop to use up to 3GB of the available RAM.

DIS Ottawa wrote:
I'm running Vista 32 bit with 4 GB RAM but Photoshop CS3 sees less than 2GB. Is this normal do you think?

For Vista it's not normal. It shouild be able to automatically recognize the max. possible RAM size. For 32 bit it's 3.25GB.
You need to check your BIAS.

Check you BIOS (not BIAS) and don't be surprised if the switch doesn't work on XP.

VladKenner wrote:
DIS Ottawa wrote:
I'm running Vista 32 bit with 4 GB RAM but Photoshop CS3 sees less than 2GB. Is this normal do you think?

For Vista it's not normal. It shouild be able to automatically recognize the max. possible RAM size. For 32 bit it's 3.25GB.
You need to check your BIAS.



Vista sees all 4GB it's CS3 that sees less than 2GB. It runs quickly with the RAM it's using but it could always be faster.

BobCollette wrote:
DIS Ottawa,

Yes, this is normal. You need to force Windows to allow applications to use up to 3GB of RAM. In XP, this is done by adding the /3GB switch in the boot.ini file. With Vista, you need to use BCDEdit to add the increaseuserva switch and set it to 3 GB. This will allow applications such as Photoshop to use up to 3GB of the available RAM.


Thanks, I'll give this a try.

8 GB should satisfy bragging rights until Photoshop 64 bit is released.

In Vista 64 bit with 8 GB, CS3 in my setup reports ~3.5 GB available.

I have 16GB on XP64. CS3 gets 4GB, and a whole ton of other apps are up, with no performance hit. Like stated, for photoshop alone to increase in performace we need a 64 bit compile of the program. Until then, excess of 4G of RAM is useless to PS alone.
I will say it is certainly nice to have lots of full res 12mp, multi layer images up in PS, have bridge cruise at full speed with tons of thumbs, a couple of my 3D modeling applications for the day job, and maybe PTGUI, or Photomatx running, watching a DVD and have windows not swap .

The more RAM the better, if you can take advantage of it. If you're using photoshop alone. 4GB on a 32bit OS, or 8GB on a 64bit OS is more than enough.

DIS Ottawa wrote
Vista sees all 4GB it's CS3 that sees less than 2GB. It runs quickly with the RAM it's using but it could always be faster.

What you're seeing is how most 32bit versions of windows work. X amount of memory is allocated to the operating system, and then a 'clean' chunk is given to applications. In the old days you could modify this behavior by editing your boot.ini

I've not used Vista, so I don't know if this works. There used to be a /3GT switch that would give 1GB to the OS, and 3GB to the application space, vs. 2 & 2

Really right now with 32-bit OS and 32 Bit CS3 you're at your limits of the capabilities of the machine.

Until 64-bit Windows is out, and 64-bit CS4 on Windows is out, you won't be able to do much better. 64-bit Vista helps some in that it does something called 'thunking' (if I'm remembering right) where the 64-bit part carves up a max limit 4GB 32-bit part in memory so that the single application gets it all.