So I have a AMD R9 270X and a AMD Athlon x4 860k its a decent PC. but when ever I play (especially minecraft) I seen on MSI afterburner and Task manager that both my gpu and CPU aren't being fully utiliezed. also in BF4 it shows that my GPU is only at 70% and my CPU is only at like 50% why is it not utilizing my hardware better?
I'm sure you will get other and better answers but for starters Minecraft is only single threaded and very RAM dependent(especially when you run as many mods as I and many others do) but not incredibly taxing on the gpu even with high res textures. As far as BF4 goes, it only utilizes a couple threads and the only suggestion I have would be to make sure your running mantle as the api since it helps a great deal and should help you get more fps and generally run smoother.
I do and I have optifine for minecraft which lets you use 4 cores to render the world.
That actually sounds pretty normal to me. You don't want games to be using too many resources as that will leave nothing for the programs/OS running in the background. This leads to laggy game play and whatnot. Also, if memory serves, Optifine only spreads the CPU usage across 2 cores, not all 4, unless things have changed fairly recently.
so I found the problem I switched from mantle to DirectX and it works awesome now.
did you get a fps increase?
I used to run an A8-6600K, which is basically a 760K with my R9 270. Easily got 120FPS with maxed out settings and 16 Chunks.
Perhaps increasing the amount of RAM dedicated to Minecraft will help.

no I did that too. but no I got Battlefield to play in ultra no by disableing mantle