Computer Noise reqs help

i built my computer last yr with these specs

-Asus p5n-d
-sony 20x dvd burner eide
-intel core 2 quad Q6600
-corsair twinx 2 gig(1gig x2)
-mass cool 8wa741 cpu fan w/ heatsink
-seagate 320 GB serial ATA HD
-Raidmax Performance Katana
-XFX geforce 8800 GT graphic card

ever since i built it, its hasnt been bothering me as much, since i usually ignore it. but lately i moved my room around and had to move my computer onto my table. my computer is Very Loud. i have 3 fans on the case one front and the other is the back, both are 120mm fans, the side contains a 80mm fan. however i dont think the sound is coming from the fans, becuase i unpluged all 3 of them, and my computer still made that noise. so that just leaves my cpu cooler fan, and the graphic card fan. i dont know which is making the noise.

I'd start out unplugging 2 of the case fans. The side 80mm and front 120mm. You can safely run your system at idle without those 2. And then you can continue to try and figure out where the problem is.

I'd checkout the PSU fan first.

Put your ear next to the PSU with the rear case fan unplugged.

i also checked the cpu fan, and i dont think its that. the leaves the graphic card last. i tried to lower the fan speed using the nvidia control panel software, however it doesnt seem to have done anything.