ok thank you for that a lot... i think i will have to get longer screws than that you... i measured the papst 120 mm fan i have and that alone is 35mm - including the fan guard - the papst fans need the screw to go through the whole of it to get to the actual thread.
aah sorry, i forgot that these were for the fans! :-[
RS do do some longer m3 screws:
http://rswww.com/cgi-bin/bv/browse/Modul…toid=-102607831
not as attractive, but 40mm should work!
edit: the other alternative would be to get some shorter srcews, and screw the fans to the rad thru just one of the two lugs at each corner, if you get my meaning? ie, not thru the full 35mm of the fan, just the 3mm or so of the surface touching the rad.