Morning.
There's CPU fan, GPU fan (which is small), a 140mm fan on top, 2x 120mm fans on the front, plus 2 HDDs. It adds up. On top of that, the CPU fan is pushed harder during the Summer months when it's hotter, and even further when I'm doing graphics work that works the CPU harder.
It isn't that loud, but it's enough to mask the sound of light to moderate rain outside.
My latest build has (2) 120mm fans on the front, (2) on the bottom, (1) in the back, and (4) on the top for the CPU liquid cooler. Of course the video card has it's own fan as well. Because all of the new components are amazingly efficient, the fans never turn above their minimum rpms and the machine stays cool. It is, without a doubt, the quietest and coolest machine I've ever had in here. The last one would raise the ambient room temperature by 10 degrees in about 15 minutes. If I was gaming it would make the room unbearably hot.
Yep, my one definitely warms up the room. Fantastic in Winter, awful in Summer.
My CPU is very efficient for what it is, but no fancy liquid cooling for me, just the stock Intel fan, which works fine. My case has an extra 120 (or is it 140?) fan on the back, but I've never had it plugged in for some reason, probably the noise. It also has room for another 120mm fan in the side, but I don't need one there. My GPU has a tiny fan on a heatsink, because it runs very efficiently, and I never push my graphics card at all (which may surprise people).
The main thing is that I'm constantly pushing my CPU with rendering. That will easily harness all four cores at 100% if I let it, which heats it up fast.