Above you see why Thermalright includes the foam pads. Because of the narrow bottom heatplate, it is a very good idea to place the pads as pictured. They help to reduce the chance of a cracked core. There are little indentations where to place the 4 pads, and you don't want the pads on the far outer edges because they would interefere with the pads on the cpu. You just peel them from the square and attach them as pictured. The stickum on them is enough to keep them attached.

First, try on the fan you wish to use with the heatsink and get use to using the clips. (fan should be blowing towards the cpu) Then try several flathead screwdrivers in the front slot on the 3-prong heatsink clip and choose one that fits it most securely. If you use a 92x25MM fan and under, you may be able to install the fan on the heatsink first, then attach the heatsink/fan to your motherboard. If using a thicker fan, like the Tornado, and if the socket is so that you have to attach the front clip near the psu, then you will need to attach the heatsink first, then the fan.

*click for larger view

Remove the plastic covering the bottom and apply your favorite thermal goop on the raised cpu core (go here for great instructions) then gently lower the rear clip over the rear mobo notches. Since the SLK heatsinks are narrow, you want to be sure the heatsink is pushed mostly towards the rear and NOT the front where the screwdriver slot is. Then gently lower the heatsink on the cpu (you may need to keep one finger on the rear clip so it doesn't move). Then use the flathead screwdriver (that you chose from before) and guide the front clip on the mobo catches. Carefully attach your fan.

* Installation is actually very simple. But I do want to stress to be sure that the heatsink is pushed towards the rear, as the pictures above on an Asus A7N8X illustrate. If not, and if the heatsink is more towards the front, then the front of the heatsink will rest on the front plastic part of the socket and that will cause the heatsink to not fully make contact with the actual cpu core. Then your temps will be higher and you could even possibly fry your cpu. Be sure the heatsink is pushed towards the rear and you will be ok.

The diagram above (click for larger view) shows which holes you use for the clips, depending on the size of the fan you will be using. But trying a fan on the heatsink before you install it, is the best way. Plus you are more familar with how the clips and fan fit. You don't want to struggle with the fan or clips while the heatsink is installed on the cpu because that could possibly lead to a cracked core.

The fins, while sturdy, are thin and far enough away from each other to allow for good airflow between them. Also notice the edge near the top of the fins where a fan goes. The fins there are all soldered together (click pic for larger view) to help keep the fins straight (better airflow) and so they won't bend as easily when attaching a fan. Because of the narrow heatplate bottom, that also allows for more airflow around the cpu. And since larger fans, like the 92mm ones (see top pics) , overhang the heatsink, that extra air helps to cool surrounding components like the mosfets, the north bridge, ram and capasitors. Depending on your mobo.

*click for larger view

Above you see the SLK900A (on the left in each pic) compared to the SLK800. Same basic design but with a few modifications. The top of the SLK900 is wider to accomodate a 92MM fan, along with more notches for various fans. One reason why the SLK900U doesn't fit on some motherboards is the contour of the fins, which is similar to the SLK800. Here you see the SLK900A has a more contoured design nearer the bottom so not to interfere with capasitors.