You probably noticed that most of the box your CPU came in was home to a heat-sink and fan assembly. Installing these can be really finicky. Before you even take the cooler out of the box, note the grey stuff on the bottom part that will actually touch the CPU, don’t smudge this. It is messy if you get it on anything, but more importantly you need it to be free of debris and stay spread the way Intel spread it at the factory. You see, the grey stuff is thermal interface compound; it helps heat move from the CPU into the heat sink. Without it, the cooler can’t do its job.
First make sure the black knobs at each corner are turned so that the slot is towards the middle of the cooler. The little white plugs to which

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they are connected won’t go in if you don’t do this. The plugs go into the four plain holes around the CPU socket, found in the yellow rectangles in picture at right.
Line up the plugs and holes. The orientation of the cooler doesn’t matter; turn it so that the wire for fan power can reach the CPU_Fan or similarly named power connector on your motherboard (check the manual if you can’t find it, it is in the red rectangle in our first picture), but not so that there is a bunch of slack that will get in the way.
Make sure the fan’s wires aren’t tangled under the cooler, then press on the corners across from one another to seat the plugs in the holes. This can require some pushing and shoving to make sure that the plugs went in correctly and the cooler is sitting flat.

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DO NOT turn the knobs! The arrows are tempting, but you only do that if you want to take off the cooler. Make sure the cooler is flush with the board, and give it a jiggle, not quite a tug, to make sure it will stay on when you switch on the
PC and the fan turns on. Remember, it only needs to hold itself in place; you won’t be doing chin-ups off the thing so no reason to yank on it.
Don’t forget to connect the fan’s power cable to the motherboard (as in the fourth picture). Make sure you use the right fan connector (as indicated by your motherboard manual) since many motherboards will report an error and refuse to proceed if a fan is not detected on the CPU.
Now relax. You have done the hard part and the rest of the build gets easier from here.