http://en.community.dell.com/owners-club/alienware/f/3746/t/19537919
I have looked this up before and can tell you I am sure some end stage dell 755's could run 8 or 9 series quads.However. The Q66 and 67's are cheap as fish and chips and perform as well as Q8300 anyway. So much so if you have a 1333 capable board it is better to BSEL mod a q6600 g0slacr chip to run at 1333.
http://www.overclockers.com/forums/showthread.php/532207-BSEL-mod-FSB-1333
Which will give around 3600 cpu marks. (sandy bridge i3 power).
This cannot be done with an 8 series, obviously.