WTF? Out of RAM?

[PorcoDuente]

i am trying to play minecraft with BDCraft 512x + Grunge BDCraft 512x, i think my computer can do this, but i am having problems.
when i put a BDCraft 512x or 256x my computer simply stop, and i need to restart it manualy, but when i put just Grunge BDCraft it works at 20 Fps, with default itens and mobs.
i am giving 6G of RAM to my minecraft.
computer setings:
MB: Asus H87M-Plus
CPU: I5 4670
GC: EVGA GTX760 SC
RAM: Vengance Corsair 2x4Gb
OS: Windows 8.1 64x

all drivers are atualized, and my java is 64x too.
i am using shadermod, vortexmap, optifine, damage indicators and forge.

Sorry if my english is wrong, i dont speak english very well :/
Sorry because the LQ images, but the host dont let me put HQ images :/

[Llama Farmer]

Sorry man, but there's no way that's going to happen. With just 6GB of RAM allocated, you'd be lucky to run plain 512x PureBDcraft by itself, let alone with GrungeBDcraft and optifine and shaders and stuff. Seeing as you only have 7GB (maybe 7.5 if you were really pushing it) that you can allocate, dedicating more RAM is not particularly viable, so your best bet is to just use lower resolution packs.

[PorcoDuente]

if you were correct i were so angry :@ because i spend a lot of money on this computer and here in brazil everything is very very expensive.
but to my happness you dont were 100% correct (:
you give-me the ideia to try remove the mods and see if it works.
i have discovered that optifine cause so much lag(its strange because i think it were to remove lag).
and shadermod is very laging too, but not comparated to optifine xD.
so i decided to remove optifine and it works at 512x+Grunge 512 with out shadermod .
but dont work with shadermod, so i tryied to do a resource pack named "Sphax PureBDCraft Itens 512x" and it is auto explicative.
so i put it up to 256xBDCraft+256xGrungeBDCraft and it works with medium quality shader at 30Fps.
Thanks Llama Farmer, im so Happy now (: