I'm running CS5 on my i7 iMac which I recently just filled with 16GB. Now, before I installed the 16GB of goodness, I wanted to see the difference so I rendered a comp (1280x720, h.264) and noted the time it took to do it. It's a pretty intensive comp with multipe 3D layers and some heavy usage of Particular. By the way, my multiprocessing settings are:
RAM reserved for other applications: 3GB
CPUs reserved for other applications: 2
RAM allocation per background CPU: 2GB
Actual CPUs that will be used: 5
Then I installed the 16GB and rendered the same comp with the same multiprocessing settings and it took just as long, well it saved me 2 seconds. Is that really the difference that an extra 8GB will do? I noticed a big difference when I went from 4GB to 8GB put not so this time around.
Now I do notice that there is a significant upgrade to my RAM previews as well as running multiple programs at the same time. So the RAM works (I got it from OWC), the computer is detecting it fine.
I tried tinkering with the multiprocessing settings, tried turning it off altogether, some variations took longer but it was never faster than having 8GB of ram.
From my understanding, for MP to be efficient, you have to have 2GB per each processor running. AE said it will be using 5 CPUs, I set it to use 2GB of RAM=10GB. I actually have more to spare since AE is telling me that the RAM available is 13GB since I reserved 3GB for other apps.
So what am I missing. Or is that it? Double my RAM to save 2 seconds? That can't be right. Are final renders not affected by upping RAM (which I was told it was supposed to). Any suggestions or insight would be great.
when you had 8gb of ram and rendering your test comp, were you seeing the ram hit the max ram limit (usually around 60%). if not then this comp wasn't using all of the 8gb, and you wouldn't see much of a performance increase for that comp.
if you want to continue benchmark testing with different ram configs and memory/multi-processing settings, you might try brian maffitt's benchmark project files:
they are a bit old, but still stress a system relatively well. it's also the same project that rob morgan used for the ae benchmark for imacs on barefeats.com, so you can see how your numbers compare to his.