Wow, 1800W power draw - that's pretty insane. I dread to think what your electricity bill is given that you have a quad Titan rig and dual 690 system too if I recall correctly!
What fans are they that you replaced the standard chassis ones in the 900D with by the way? Are they the Corsair AF120's? I'm considering replacing the ones in my 900D with them, but I'll probably go with the low noise AP120's (think that's what they're called, can't remember now).
Yes they are the AF120's
http://www.overclockers.co.uk/showproduct.php?prodid=FG-004-CS&groupid=701&catid=2331&subcat=4
As to my elec bill, most of the time I just use the GTX 690s.