[Pros] Strong mechanical attachment. Easy removal/rework. Applies a preload to the thermal interface material, improving thermal performance. [Cons] Requires holes in the board or solder anchors. More expensive than tape or epoxy. Custom designs. [Cost] Low [Method] 
Wire form Z-clips
T h e r m a l t a p e
E p o x y
W i r e f o r m Z - c l i p s
C l i p - o n
P u s h p i n w i t h c o m p r e s s i o n s p r i n g s
S t a n d - o f f s w i t h c o m p r e s s i o n s p r i n g s