I've had a Q9450 on an Asus Rampage Formula (X48) for 2 weeks. Performs well, overclock so easy...a caveman could do it. Coolers? I've used my Zalman 9700NT, Xigmatek S1283, and finally a TRUE. If you don't want to spend the ~$300US for a Rampage consider the Asus Maximus Formula (X38) for $200-$250.
How does the Zalman 9700NT fit on the Rampage Formula? does it interfer with the mobo heatsink or is it just a tight fit??