should I get 4G of RAM

I currently have 2 G of RAM.

Im loking for ways to improve lightroom, which I love.. . another 2 G of RAM is stupidly cheap these days and I have two slots open on my motherboard...

would it make a difference? Would windows even see / use the extra RAM?
Does it matter if I have 32 or 64 bit Windows?

a single program or process can only address 2 gb of RAM on a 32 bit operating system, and it's even less with wondows. however, seeing as how the OS is eating up a good chuck of ram itself, adding more ram couldn't hurt!

Go for it.
XP Pro 32bit shows 3.5gigs of memory available with 4gigs installed. 64bit might show all of it, I don't know as I haven't installed 64bit on any machine.
Vista should show all 4gigs available.

all 32bit OS won't show the full 4GB, only 64bit OS will allow you to use the full 4GB.

Does the 32 bit / 64 bit windows operating system difference make a difference for the RAM that is available? Ie does it change how the RAM is used, or just how much CAN be used? It might be worth getting 64 bit windows if I am so inclined to increase the amount of RAM...

To be honest, i don't know. I think it doens't really make a difference how the memory is used in the 32bit vs. 64bit. Although you would think that they would optimize it in a way for the 64bit right? One thing i do know is that you won't be able to use the 4GB in a 32bit environment, so that kinda answers the question too right?
Why don't you state what your computer specs are and maybe there's another way to improve your computer's performance.

bowlesbe wrote in post #3499162
Does the 32 bit / 64 bit windows operating system difference make a difference for the RAM that is available? Ie does it change how the RAM is used, or just how much CAN be used? It might be worth getting 64 bit windows if I am so inclined to increase the amount of RAM...

Photoshop is 32-bit only and I suspect, but do not know for certain, that Lightroom is as well. It wouldn't do any good to use a 64-bit OS for apps that can only do 32 bit addressing. Of course, it might speed up other 64-bit tasks and that might result in some performance enhancement, but I don't know how significant it would be.

64-bit Operating systems usually run 32-bit applications just fine.

you have add the /3gb switch to your boot.ini file if you put over 3gb in your 32-bit system.

In addition, whether or not you will benefit from 2gb of additional ram depends on your motherboard chipset, CPU, the type of ram you are currently running and the memory timings of the ram. It also often is affected by whether or not each ram stick is the same build and revision.

I bought two gig of DDR ram in a matched set to add to a system that already had 1gig of DDR ram in a matched set. While I'm able to run all 3gb in the system, the memory bandwidth is cut to less than half of what it is with just the 2gb installed.

So I'm running on the 2gb only until I have time to do more testing.

Bottom line, while everyone is talking about how much memory Photoshop needs to run optimally, Adobes site has some interesting info regarding that in the support section. You should go there and take a look.

Before buying any additional ram for your system do some research on your components and look specifically for information on what happens to the ram on your motherboard if you populate more than two slots, particularly if you are using dual data rate ram.

For more info about CS2 on a 64-bit system and ram usage on both 32-bit & 64-bit systems Look Here.

Unless anyone has further insight:

I am using:

core 2 duo 2.13mhz supported by a asus motherboard (p5b; chipset 775)

2 500GB disks set up with two RAID partitions. RAID 0 (35GB) for windows and apps), RAID 1 (~450GB) for photos. This way I get secure storage for critical data and a faster partition for programs. (Although to be honest, not sure if I notice the increased speed fo the RAID 0).

Found it interesting though cuz the site recommended above says that the cs2 scratch disk should be a RAID 0 partition for fastest performance, yet it ALSO says it should be different from the windows paging file (which it isnt, in my case).

I also have 2 gigs of RAM... and 2 open slots... trying to figure out whether to populate them...

I am still confused about this 64 bit business... and whether I should learn more about it. Its interesting the that Mac Pro's seem to use exclusively Xeon 64 bit processors... i wonder why that is.

Further insight in the P5B motherboard can be found here at Corsairs support forums.

I don't think you will find an answer you like.

Example. I'm running an Athlon 64 4000+ CPU. I ran memtest on the system with 2gb of TwinX3200-C2PT with memory timings set at 2-2-2-5 and 2T disable in bios. Everything is fine. SiSandra and Everest Home edition benchmark the memory bandwidth in the ~6000 MB/s range.

When adding 1gb of TwinX3200-XLPT into the system (yep, you got it, populating all four memory slots) the memory bandwidth is knocked down to a little over 2800 MB/s.

Memtest reports different numbers for memory bandwidth than SiSandra and Everest but still shows the same basic bandwidth hit.

CPU-Z adds some useful detail to the help sort out what happened.

While running 2gb of match pair DDR ram at 2-2-2-5-1T, the ram bus is 200MHz x 2 for 400MHz. After adding the original gig back into the system at 2-2-2-5, the bios/cpu controller set 1T to 2T and halved the Mhz of the ram so I am 3gb running stable but without the speed of 2gb alone.

So the question really is..., Will you see a performance gain in CS2/CS3 with the additional ram operating at a lower bandwidth or not?

Reading/writing Ram is still far faster than reading/writing a scratch disk.

Haven't set a test up for batch post processing to check the two different ram configs so at this point I don't know definitively what the answer is.

Ken