I follow the same ethos.....keep it big and thus under-stressed.

Corsair ASX 1200I Platinum Certified 1200w Modular PSU. - Fan only ever runs on boot...then goes to sleep.

Noctua NH-D14 SE2011 LGA2011 Cooler - pretty much the same re running.

The case is effectively its own heat-sink [Thermaltake Level 10 Titanium LE] and being Al plate [not tin] you don't hear to much anyway.

It's disconcerting though when I get up each morning....have to look for the lights to even know it's still on...

On the flipside there is nothing more disconcerting when you hear a strange new noise the machine never made before, no matter how quiet it might be. Had a laptop start making a strange noise for a couple of days, the thing was brand new as well.

I have my PC under my desk, but it's fairly quiet while I work or play games. I rarely have a quiet office though as I tend to listen to radio shows while I work as it keeps me pretty productive.

I have an Alienware Alpha in my living room and it's also quiet, although its fans can go crazy when it's under heavy load. I gave access to my Plex Media Server to my family and friends, so if I had to guess what the heavy load was, it's probably multiple streams going at once since I don't use it for anything else (outside of streaming games via Steam, of course).

I did something similar, but instead of fans that aren't running until they're needed, I have fans that basically run slowly and have advanced bearings so that you can't hear them when they're running at their minimum speed. Those slow fans still keep the computer at under 55c under moderate load without increasing their speed. The weakest link is the GPU though, since it's a lot harder to replace the fans for GPUs than CPU and Case fans, so when the GPU is under load it still gets loud. 

When I'm running the GPU at full load though, I have my headphones on and can't hear the noise as clearly.

All Noctua fans (80mmx2, 120mm, 200mm) and Noctua heatsink in a Mini-ITX case. I run an 8-core chip at stock speeds, rated at 65w.

My Mac is virtually silent. All my PCs have varying noise levels. Only one that is nearly silent is in a noise dampening case. Phanteks.

Mine uses liquid cooling, can't hear anything at all. 

This is the first machine I went with liquid cooling and I love it! My CPU stays at low temps under load, and I don't hear a thing. Next, I'm going to get a liquid cooled video card.