Jim,
I know you didn’t ask me specifically, but I thought I would chime in.
The biggest gain in PS will be achieved, all other things being equal, by optimized data transfer from the hard drive. This is theoretical based on the way photoshop works. In practice, noticable benefit is only reported in the most extreme of cicumstances.
There is always a tendancy to get the absolute most optimized specs, but in practice, the gain isn’t often obvious, except in extreme cases.
There’s another short thread in this forum that discusses this very issue HERE <
http://www.adobeforums.com/cgi-bin/webx?14@@.3bb59750/0>.
An interesting thing I found was that it appears the P/S stresses your CPU much more
Absolutely. There is no other commercial software that will strain the nooks and cranny’s of a system like Photoshop (I got that from Chris Cox who appears on the splash screen when PS loads).
I always thought that everything was "done" in memory but that’s not true.
You are correct. PS doesn’t work quite the same way that most windows programs work. Well, it does, but the processing power of photoshop relies on the use of dedicated HD space. Dedicated in as much as it creates a temp file specifically for it’s use and swaps information to and fro.
I always thought that I wanted to allocate as much RAM as I could to CS
You can end up choking RAM required by the OS and other processes if it’s set too high. IOW, there’s a "sweetspot". Where that sweetspot is on your system depends on how much ram, and what other processes are running. For some systems, it’ll be 50%, for others, 70, and yet for some, 90. If you have enough ram, and can do the math, you can find your sweetspot. In general, the rule of thum is to set it at 70-75%, but you know how rules of thumbs go…
Peace,
Tony