Jason Snell, writing for Six Colours:
When running HandBrake, the fan on my 5K iMac would always crank up and was quite audible when it did so. So far as I can tell, the iMac Pro’s fan may always be running, but it’s amazingly quiet. In my normal office environment, I can’t hear it—only when I spun the iMac Pro around and listened with all other devices off could I hear it, faintly blowing. When HandBrake was running at full speed, the iMac Pro sounded pretty much the same—but the air coming out of the vents on the back was definitely warmer!
I wonder how well the components inside that unnecessarily small case will fare from the heat over an extended period of time. This is my biggest iMac complaint — the back of the display could be both thicker and deeper, like the older iMacs. I’ll admit it looks good, but I’ll take cooler running internals over visual aesthetics every day of the week.