CS4, XP SP3 (32 bit) and over 4 gb ram

Question

I have an XP SP3 system with quad power and 4gb ram at present.
I found this in Memory allocation and usage (Photoshop CS2)
If you have more than 4 GB (to 6 GB (Windows) or 8 GB (Mac OS)), the RAM above 4 GB is used by the operating system as a cache for the Photoshop scratch disk data. Data that previously was written directly to the hard disk by Photoshop, is now cached in this high RAM before being written to the hard disk by the operating system. If you are working with files large enough to take advantage of these extra 2 GB of RAM, the RAM cache can speed performance of Photoshop.
This seems to refer to 64 bit but I was told it applied to 32 bit and 8gb. Is any of this true for 32 bit XP?
Thanks,
RON C

Answer 1

On Fri, 24 Oct 2008 12:06:53 -0700, [email protected] wrote:
> If you have more than 4 GB (to 6 GB (Windows) or 8 GB (Mac OS)), the RAM above
> 4 GB is used by the operating system as a cache ...
>
> Is any of this true for 32 bit XP?
This is talking about a 32 bit app running on a 64 bit operating system.
The gist of it is that a 32 bit app, benefits indirectly from >4GB of
memory, only if the OS is 64 bit. Likewise, on 32 bit systems, there is a
similar benefit to having 4GB of RAM, even though Photoshop cannot see >
2GB.
Re /3GB: normally the OS splits the 4GB address space 50/50 with
applications. The /3GB switch allows you to shift the balance. Photoshop
can handle a larger image, but, as Jeff says, the performance suffers.
It's useful though. If you have a large image that you must process by
hook or by crook, the /3GB switch allows you to do so without running out
of RAM. I do this occasionally when I get a very large image from a
customer - generally it's go have a cup of coffee, or lunch, while the
large image is being loaded and resized. When I get back, the image is
manageable and I can reboot without the /3GB switch. I've done this on a
system with only 1 GB of ram, processing images between 50 and 100
megapixels.
FYI - the boot.ini that I use is:
[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP
Professional" /noexecute=optin /fastdetect
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP
Professional 3GB" /fastdetect /3GB /USERVA=2944 /NoExecute=OptIn
Warning: It's easy to brick your system when modifying boot.ini. Be
absolutely sure that you can boot from another drive and restore your
original file.
Images are getting larger. 32 bits is a pain. Viva la 64 bits!