I have a mini-ITX system. I like it because it has the power and fits in a bag.
My case is Ncase M1, full waterclooled(MB, CPU, GPU), just a little bit bigger than a Xbox One.
CPU Temps when crazy gaming stays around 60c, topping at 70c.
GPU temps never goes above 50c.
CPU: i7 4770k at 4.2ghz...