Upgrade CPU or GPU, or even both?

ivideo1011

Honorable
Jul 5, 2013
57
0
10,640
I'm looking to upgrade my gaming rig, and I don't know what I should upgrade for under $400. Should I switch over to Intel and get an i7 4770k with a new motherboard? Or stick with my current AMD processor and just upgrade my GPU? My budget is $400, but I don't know if I should upgrade my CPU and change my motherboard and wait later to upgrade my GPU. It would mean a lot to me if someone could help, thank you for your time.