WELL.... i cant run a 512x512 texture pack, but i definitely should, i have a really good PC that i put alot of hard work into, i just wanna test it... i get all the way to the loading part where it crashes, and it doesnt say "Minecraft has ran out of Memory!" it crashes, and i dont lag AT ALL when im on the title screen with it, i get 200+ frames, here are my spec just in case.

Intel Pentium G860 Sandy Bridge 3.0GHz LGA 1155 65W Dual-Core Desktop Processor Intel HD Graphics
8gb ddr3 ram
Radeon HD 5770 1GB 128-bit GDDR5 PCI Express 2.0 x16
2 hard drives, both 70 gb
good motherboard(im not sure, it was my brother and im still learning, its biostar tho)
650W powersupply

HALP, i know i can run this, i play Far Cry 3 on ULTRA with DX11 on :3