Im surprised to hear about memory issues. I only have 8 gigs of ram ddr3 2400 but have 3 mining instances open, had 2 plotting instances (cpu) but one now, watching hd movie on my tv through video card , bfgminer using my 2 u2+ miners, utorrent seeding lots of files, multiple IE windows open, wallet running and few other little apps and my physical memory says 28% used....
I really dont know why the miner needs so much ram, i tried everything from 300 to 1000 in the settings, seems to work the longest with 650mb.
I have an old Platform (X58) with tripplechannel and 6GB of ram.
Maybe because of tripplechannel theres an issue.
It didn´t acure while i had less then 4TB plottet.
Sometimes my RAM usage is up to 100% while mining and at some point it crashes.
I ordert 12gb of ram last week, should arrive totday.
I hope this will solve the problem, but honestly i dont think so, will see.