Switch off the console.
Open the console and locate the PC motherboard
Identify that the console has a Gigabyte Heat-sink

 
ONLY THIS TYPE OF HEAT-SINK REQUIRES THE BRACKET

Fit the bracket over the pegs of the heat-sink/fan assembly and press down
Make sure that the heat-sink stays in contact with the CPU. 
If the heat-sink has to be tilted in any way to engage the bracket it is not placed correctly. Un-clip the Heat sink clamps and reposition. Refit the heat-sink clamps 

Fit two M3x10 screws with flat and spring washers to the back

Switch on the console and check that the fan runs free.
Close the console and tighten the Dzus screws.