There's one thing missing from your build: an OS. That basically reduces the budget to $300.
I recommend getting rid of the GPU, go for an A10, and getting a compatible motherboard.
Oh I already have a OS sitting around in my usb so excluding the OS, $400 budget would be accurate.
perfect then.. go through some videos in utube.. and go through my build.. find the parts which suits u better.. u will have a pretty good time gaming LOL..