Minecraft FPS Issues

Hello all. Having some troubles. I used to have an Asus laptop. It had 8GB RAM, an intel 2.0 GHz 4 core processor, and an Nvidia video card. I recently built a custom computer. It has 16GB RAM, an AMD 4.0 GHz 8 core processor, and an Nvidia GTX 770 2 GB video card. I don't remember the Asus's card, but my new one is for a fact better. WIth the Asus laptop on lowest settings, I got around 300 FPS. On my current one, it gets around 60. This makes absolutely no sense to me. Please help me out. ALSO, I want to allocate more RAM into Minecraft, but it won't let me put in more than 1GB.

Thanks an advance,
Spydex