Thanks for the answer mate. I ended up deciding to spend a little bit more and go for the Gigabyte Z270 Gaming K3 and with ASUS GTX 1060 DUAL.
But I'm still looking for a case / PSU combination. I'm aware the cases such as CM K280 that come with a PSU included are really subpar, but I don't have any room in my budget now that I picked more expensive mobo + gpu, and those PSU included cases are really the saving grace for me atm.
I'm not sure where to open a new thread about it, so I'll ask here. What do you think about the Corsair Carbide 100R or Thermaltake Versa H23? They both come with a 500W included PSU, but there are no specifications as to what the actual PSU model is.
You maybe not from USA, because I can't find the info about them too. If you have to choose one from those, maybe take the Corsair Carbide 100R.
But if you have tight budget, recommend you to buy the z270 HD3, and get a better PSU, because GPU/CPU/PSU are important for games, the MB is not important. For your PC, a good
500W PSU is more than enough, even the 400W too. And don't cut the corner on the PSU, which is the heart of the PC. Like you said those PSU is really subpar, if they are, you will end up buy other one, and you will spend more.