Try turning it off.....hehehe   Hmmmmm to do so without impairing performance would probably require making a duct system inside your case.  (just an idea)  I dunno that "lubing" your fan would quiet it, unless it is the bearings, but all that noise is from a lot of air being moved.  You can trying squirting a little wd-40 or your favorite brand of lubricant under the sticker on top (it covers the bearing opening)