Neat!
All fans have a 'dead spot' immediately in front of the motor hub.
The main 'heat spot' on the Parallella comes from the Zynq (although other chips get warm too).
Going by your picture, it looks like the 'dead spot' is positioned over the Zynq 'heat spot'.
Likely that under the hub there is very little air-flow - just where you need it most!
Suggest you put a spacer between the fan and the sink, maybe 1-2 cm longer screws, so that you get the air-flow.
Perhaps not so neat - but probably lower temp.
Cheers
