I enjoyed earlier days of "Silent PC" building, ten or fifteen years ago. For example, building a silent tower or desktop for a DAW or softsynth back then in a recording/studio environment required some ingenuity. SSD? Not on a hobbiest budget. I recall one build, not mine, fully immersed in a bucket of oil (mineral?) for passive heat dispersion.
Today, as a new reference point, any MacBook Pro within the last few years may qualify as truly silent for many people's everyday usage. It does for me. And when I do heat up the CPU/GPU with heavy tasks, the fans spin up but then they go away completely as soon as the hard work is done. Back to silent.
No more spinning platters or crappy fan bearings or poorly engineering airflow nowadays. :-)
There's no hacker pride in buying off-the-shelf, so the performance bar for DIY is higher. Progress!