An i5-8400 is a locked CPU (no overclocking), so look to an H370 or B360 motherboard if you opt for that CPU.
As for the use-case; gaming, that's a very solid build (although PSU is unknown?).
BUT, for streaming, the 6 core w/ no hyper-threading nature of the i5 is less than optimal. An i7 on the Intel front (or Ryzen5 2600/X on the AMD front) might be a more worthwhile consideration as they're 6c/12t.