Re: please tell me what u think of this build.
What I would do, is buy 2GB of RAM. Test it out. See if you're satisfied with it. If not, then get more. I'm pretty sure, it will run very smoothly with 2GB of RAM, if you're using this computer for general usage and gaming.
If you're satisfied with 2GB of RAM, then that would of saved you money, rather than spending all at once for 4GB of RAM.
3770K | ASUS STRIX GTX 1080 | DDR3-1600 16GB | CORSAIR 650D | CORSAIR HX 850W | CORSAIR H100 | SOUND BLASTER Z | ASROCK EXTREME4 GEN3