I love my ginormous DG-87 case.  I have had it since it nearly came out.  I have been having issues with the back case fans, the original that came with my case  One of them is really really really really (I mean REALLY) loud and another sometimes I can't tell if it is running or not.  What is the easiest way to replace these.  They both have the metal grates over them to help "prevent" dust I am sure.
 
I have not dug into the wiring traced in the case so I seem to recall some people having issues getting the wiring and such traced and replacing the fans or is there something else that I am missing?  Suggestions for high powered good cooling fans.  I might replace the front 3 at the same time, though no known problems with those so far.  I do have a radiator at the top but that should not affect anything for the case.
 
Ideas and suggestions are greatly welcome.