If using Windows, get a second 4gb stick...4gb is enough for linux, barely cuts it for win.
Really don't get this memory thing. I have eight rigs, each with four cards, all running (linux) with 1GB. Vertminer never uses over 250mb, including caches. Adding unused ram isn't going to do anything.
with win is different you know, you just open 4 chrome page and bam 2.5 gb, also when i'm mining and i reach 4gb+(because i open multiple chrome page or other things) the system tell me there is insufficient memory and i have 8gb total
maybe he reserve 4gb for the gpu