AE / AME (CC) won't render a simple 3:00 min video. Why?

My setup:

MacBook Pro 2.6GHz i7

16 GB RAM

Internal 250 SSD with 65GB available

External 3TB FireWire 800 drive

I have tried every possible combination of memory management within AfterEffect for a simple 3:00 HD video, which I have rendered before, and it keeps running out of RAM.

Can someone please tell me the optimal setup for my machine and what my memory and AE multi-processing allocations should be?

Thanks in advance!

D