It's fine really. When you build new system there's always that feeling, that it should be better than average (and maybe unrealistic expectations), but really it's all good.
That said, in summer we had quite a heatwave (~33 C ambient room temp), and Corsairs SF450 PSU had blown one of it's transistors.
It was a cheap fix re-soldering specific part, but still, it happened. After that, I tuned a fans a little bit for a little more airflow, because all of them had lowest possible RPM settings for lowest possible noise levels.
With the new Coffee Lake CPU's I would guess, the temps should be even better.
I can't remember of the top of my head specific numbers, but in gaming CPU/GPU doesn't go above 65/80 C. In stress tests, highest CPU temp that I saw, was 75-80 C, if I'm not mistaken.
