So I'm trying to figure something out: I have a comp that is roughly 6000x3000, and when I RAM preview at 1/3 resolution I get about 160 frames before the preview begins to loop. I have multithreaded hex core pc (12 logical, 6 physical cpus) and 64 GB RAM. running win 7 x64 pro. In my PC monitor, the RAM only fills up to about 20 GB before it starts looping. It doesn't seem to matter what the MP settings are, how many alternate cores are reserved, how much RAM per core etc. I can't get more than 154 frames at 1/3 res preview. Shouldn't the RAM fill up completely before I run out of preview? The comp is using particular and has a couple tens of thousands of particles, which isn't really that many. Rendering is fine and uses all available mem. Turn MP off and behavior is as expected, using all RAM. But slooow. Any ideas about why I can't get more frames in MP? Thanks,