Speeding up a dualcore G5 to work with large Photoshop files

Question

Hi
I have a 2.3Ghz dualcore G5 (the one that came out late 2005).
I'm working on a bunch of large format film scans (500Mb +) in Photoshop CS2, and I'm trying to speed things up.
This last week I've installed two upgrades that have helped get things moving - first I upgraded the RAM from 4.5Gb to 12 Gb, then I installed a second hard drive (Seagate 7200.11 500Gb, with jumper in place) to use as a dedicated scratch disk.
Both upgrades have given a significant speed boost, but I'm now wondering what else I can do????
I want to speed up the time that it takes to open and save these large scans.
My first thought was to buy a second Seagate 500Gb drive as a replacement for the original 250Gb WD drive. I would then have two 500Gb internal drives that I could configure as a RAID 0 array with disk utility. I would then clone my original 250Gb onto the RAID 0 drives with Super Duper.
Wouldn't such a set-up double the speed of opening and saving large Photoshop files?
I realise that with RAID 0 there is an increased chance of data loss from disk failure (double the chance?), but if I back up daily to a 1Tb external that should be ok, no?
Or should my next move to be to utilise the PCI-E slots (which I don't really understand)????
Thanks for any advice you can offer.
Richard

Answer 1

In my G5 Quad, I find the fastest Photoshop performance overall- especially with large-file open and saves, occurs when the setup is as follows:
Startup disk is a 2 x 150G Raptor RAID0 which contains the system, apps, and all user files- including the image file being worked on.
PS scratch is then pointed either to a third fast drive or to an external RAID0 array. This setup is substantially faster than:
....the safer method of using one Raptor for system and apps, and the other for user and image files, with a third drive for PS scratch.
With a really fast large scratch disk, you can sometimes put the image file on the same volume as the scratch file, open and save it from there, and you'll get a bit of an additional boost so long as the scratch disk is faster than the startup disk.
For CS3 (I believe it works for CS2 as well), a performance plugin called DisableScratchCompress.plugin is available which can also speed things up with a fast scratch disk. I found that using this plugin speeded things up but only if the image file was opened/saved from the first config I mentioned; it was slower if placed on the scratch disk while using the DSC plugin.
More here: Photoshop Acceleration Basics
Of course if you stripe a disk with data, be sure to frequently back it up..:)