HelpMinecraft RAM stuck at 455MB?

So when I am trying to allocate more ram to minecraft, whatever I do it stays at 455MB when I press F3 in game.
I have 8GB installed and I am trying to allocate any amount really. 2GB, 3GB, 4GB but it stays at 455MB.
I have Java 7 Update 60 32bit and 64bit.
The mods I have installed on minecraft: Optifine, Shaders
I completely reinstalled minecraft, tried to change ram without any mods, on a clean minecraft and nothing.
I really have no clue what could be the problem.
My pc specs:
RAM: 8GB
GPU: GTX 760
CPU: Intel Core i7 4820K @ 3.70GHz

Have you been using the launcher options?

Allocating more ram didn't do much when I tried that so I suggest making a 1gb ramdisk (that will make it ~400% faster) for Minecraft.
http://www.mpgh.net/forum/showthread.php?t=827418

Check your java, i was playing Tekkit on the Technic pack and it only let me dedicate 512MB of ram for Minecraft. Turns out when i updated my java, it downloaded the 32 bit version for some odd reason; regarding your issue, I would re-download java and make sure you have the 64 bit version.

Check inside your clients settings.. Look for a Gear looking thing... You should find something in there.