Still, I don't understand how you can live with all that noise. Maybe you have gotten used to the noise.
For me, the standard always goes high, every month. When I had the old PC, I had 2 case fans at first. It wasn't that bad. After a while, I couldn't bare it. I could hear the PC running from about 7-8 meters away. So, I removed one fan. It got a bit better, but after a while, I still could hear the damn thing from 7-8 meters away. Then I removed another fan, and used 7V on the only other case fan available. It lowered the noise a lot. But still, after a while, I felt it was still irritating, mainly when I left the PC on while going to bed. (I didn't have ADSL those days, but I encoded a lot of DVDs at night). Anyway, the components inside the PC were getting toasted as there were not much cooling happening. But I couldn't tolerate the damn noise.
Anyway, now with this new PC, I was amazed how quite it was. Since things were running cool inside, I changed the case fan's voltage to 7V, and it reduced the noise further. I even couldn't believe how silent the video card's fan was, compared to the 9700Pro I had couple of years ago. But, now I'm again feeling it is not as quiet as it was last month. Now I'm pretty sure it has something to do with the ear.
Unless I move to a 100% passive cooled system, I will never feel the PC is "quiet"..