[NAME]  Firstly, don't post your Service Tag. To answer your main question, the CPU fan connection is industry standard 4-pin PWM.  My XPS 8900 is happily running with an Arctic Freezer i13 X CO fitted. 
Hi, I see a lot of posts around the Internet about how Dell use a proprietary pin out for the CPU fan header. However, the stock CPU fan on my XPS8900 is four-pin and colour coded Black-Red-Yellow-Blue. To me this appears to be absolutely standard; Does it mean that I could replace it with an aftermarket fan without issue?
XPS 8900 CPU Fan