not sure if this helps any, I just finished building a model that was about 50mill poly. wanted to get as much
detail as possible, input was about 45 images from a 5D mark 2, 21 megapixel, using ultra high reconstruction, I was getting instant crashing on my machine with 48gig ram, luckily the mother board supported up to 192gig ram, so managed to fill it up to capacity, final usage was around 130 gig, there is definatly an issue with virtual memory, as soon as it hit's swap it almost always crashes on me.