So I'm finally looking into updating or replacing my main PC with something faster... and quieter. I actually turned the sucker off the other night, and I was stunned by the sudden, and pleasant, silence. Ahhhh...
Luckily there's a booming silent-PC, quiet-computing movement going on, and there are many websites reviewing cases, fans, power supplies, CPU coolers, and other pieces/parts that can help you quiet down a whining, hissing beast or build a whispering phantom from scratch.
I just now opened my case and shined a flashlight in to take inventory of my current situation, and as the light shone through the blades of my whooshing, buzzing CPU fan, I saw the heatsink underneath thoroughly caked with fine dust. I have cleaned out this PC occasionally, but never thought to peer into the darkness behind that little fan. Stupidly, I blew all the crud out with canned air. Now I can hardly breathe in my den, and shortly everything will be covered with said crud. But ya know what? That fan is about 75% quieter now. It had been loudly grinding away against all that impacted dander.
It's still not a "silent PC" by far, but it sounds a bit less like a model airplane taking off now. Good ROI on that canned air.