So I have recently added some shaders to minecraft, and it only runs at 13FPS, so I went into minecraft, and went into the JVM Arguments, and typed "-Xmx2G" to add more RAM, and then it gave me an error message. The error message said "Error: Could not create the Java Virtual Machine. Error: A fatal exception has occurred. Program will exit." and then it takes me back to the launcher. I checked to see if it was because I didn't have enough RAM, but I DO have enough RAM. My PC specs clearly state "RAM: 8 gigabytes (7.21 usable). So my computer has 7.21 gigs of usable RAM, and it won't let me allocate 2 to minecraft. Can I fix this?
If you have a 64bit OS (and if you don't all that RAM is wasted), then you need to download, install and use 64bit Java to go above ~1.5G of heap.