Ok, so this is something new to me, ive never had a memory issue since the botched v7 of the FTB Mindcrack pack.
While i dont have any screenshots right now, because i closed the program to prevent it crashing my system, it appears this pack (or is it the game/java itself?) suffers from a horrendous memory leak. (the reason i suggest pack, is because i run Serendipity Unlimited on the Technic Launcher which has no qualm with running on 4gb memory, having more than 2x the mods of this pack, i do not get memory issues there and i also use a 128x128 texturepack that has textures for roughly 75% of the mods.)
My FTB Jre setting is and always has had 4GB (1/2) of my system memory reserved for it, though ive noticed after a few hours of play that the java application in the Windows Task Manager is reading well over 5.4GB in memory consumption, pushing my system over 95% ram usage (at idle, its barely 7-15% while a freshly loaded instance pushes this to approx 40%)
At this point, if i continue to play the game begins to stutter horribly - so i have no choice but to restart a fresh instance of minecraft.
The only thing in this pack that i can think of that would cause this prob is the TE item ducts back stuffing
so if you are using item ducts check to see if they are getting back stuffed. If so creat a dence loop back into the input chest