This was my first Mini-ITX build and my 4th build overall.
The goal of this build can be summarized as "compact and powerful". My end goal was to be able to accomplish a silent, small streaming rig capable of streaming at 1080p/4K and record/edit videos simultaneously. You can also run ANY game out there on this PC, but I already have a separate computer just for gaming.
The CPU idles in the 22-32C range, loads at around 50C when streaming, and around 60C in the more intense Cinebench R15 tests. The GPUs idle around 28-35C and rarely go above 50C.
The Asus Z170I PRO is a phenomenal motherboard, and is the centerpiece of this build. It was a prerequisite for making my computer "small". This board provides wired, wireless and bluetooth connectivity and has an excellent BIOS GUI.
The GTX 1080 and the Corsair Vengeance LPX RAMs were salvaged from an older computer. RAM stock frequencies are doing just fine for now.
The Corsair SF600W is probably the best PSU for this build. Can provide up to 600W and it's fairly small compared with other PSUs. Not so cheap though. If you decide to install this PSU, make sure you buy an ATX to SFX PSU adapter to install this SFX PSU in your Mini-ITX case.
The Cooler Master Seidon 120M does the job. No issues installing or fitting the radiator and fans on the front. My only complaint is that the fan cable is really short. I had to buy an extra 4-pin (PWM) fan extension cable.
The Cooler Master Elite 130 case (or bigger) is a MOST in order to install the GTX 1080. This particular case works great for my build, and I like the case design for better airflow in my PC.