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Affixing the cooler
CPU coolers come in all shapes and sizes, from the relatively basic stock models sold with AMD and Intel processors to more extravagant designs offered by third-party vendors. The standard heatsinks work just fine, but they don't cool as well—or as quietly—as even budget aftermarket models, let alone the more exotic stuff. We've gathered a handful of different coolers to illustrate how the most popular mounting mechanisms work. Let's start with a stock AMD cooler.

AMD sockets have integrated heatsink brackets that are screwed onto the motherboard. Note the outward-facing tab in the middle of each one. We'll be hooking the cooler onto those tabs using the ends of the metal beam running the length of the heatsink.

Place the cooler on the CPU, lining up the beam with the plastic tabs. One end of the beam will have a lever, which should be open. Hook the other end of the beam onto its corresponding tab before doing the same to the levered side. When the beam is attached at both ends, flip the lever to lock the cooler onto the socket.

Once the cooler is secure, plug the fan into the corresponding pin cluster—referred to as a header—on the motherboard. There should be a three- or four-pin header marked "CPU" near the socket; the motherboard manual will indicate its precise location. Note whether the fan is a three- or four-pin unit, commonly called DC and PWM, respectively. That information may come in handy when you adjust fan speeds in the motherboard firmware.

Don't worry if the number of pins in the motherboard header doesn't match the fan plug. DC fans work just fine in PWM headers as long as you line up the plastic tab on the header with the ridges on the fan connector. You can also use a PWM fan in a DC header by lining up the same plastic tab. However, DC headers don't support speed control for PWM fans.

To remove the heatsink, simply flip back the lever, unlatch the tabs, and lift the cooler off the socket. Some thermal compounds have a tendency to stick, so lift carefully to ensure the CPU stays in the socket. Yanking the cooler off the socket with the processor attached can bend or otherwise damage the pins on the CPU. If the heatsink feels bonded to the CPU, try rotating it back and forth to break the grip. Depending on the cooler design, you may be able to remove the motherboard's heatsink retention bracket to allow for more rotation.

Intel's stock coolers are quite different from AMD's. There's no mounting bracket around the socket, just four holes in the motherboard. Matching posts on the heatsink anchor it directly to the circuit board.

Before the heatsink is mounted, its push pins need to be primed. At the top of each post sits a plastic cap. Rotate each cap counter-clockwise and tug up to ensure the attached black pin is recessed in the post. Then, rotate the caps clockwise. The posts turn only 90 degrees, so don't try to spin the caps.

Now, lower the cooler onto the socket, taking care to line up the posts with the holes in the motherboard. When the cooler is resting comfortably, push the posts down one at a time. Secure the pins on opposite corners first, much like you would when bolting a wheel onto a car. The pins should make an audible click when they lock into place.

To make sure the push pins are secure, flip the motherboard. As the picture above illustrates, you should see a protruding black tip pushing apart the translucent pieces that anchor the push pin.

Now that the heatsink is mounted, it's time to plug in the fan. Follow the same procedure we discussed with the AMD cooler.

Need to remove the cooler? Rotate the posts counter-clockwise, pull up to release the pins, and then lift the cooler off the socket. The posts are slotted to accept a flat-head screwdriver if the surrounding area is too cramped for your fingers. If the pins are all loose but the cooler still feels bonded to the CPU, rotate the heatsink. The twisting motion usually breaks the grip of sticky compounds. Thanks to the LGA socket's CPU retention bracket, there's no risk of accidentally pulling out the processor with the heatsink attached—or damaging the socket's pins in the process.

A stock Intel cooler (left), a stock AMD unit (middle), and an aftermarket Corsair tower (right)

Compared to aftermarket equivalents, the stock coolers sold with AMD and Intel processors are relatively small. The fans sit on top of the heatsinks, blowing air down toward the fins, perpendicular to the surface of the motherboard. Aftermarket solutions turn this concept on its ear; they're typically made up of a tall radiator that rises up from the socket, with one or two fans pushing air across the fins, parallel to the motherboard. The increased surface area of the larger radiator, coupled with the greater airflow generated by the larger spinner(s), can result in lower CPU temperatures and reduced fan noise. Win-win.

Aftermarket coolers sometimes use similar mounting mechanisms to their stock counterparts, but increasingly, newer designs rely on custom back plate hardware. If you have an aftermarket cooler, follow the specific instructions associated with it. This is one of those situations where it pays to read the manual.

Most manufacturers have different spins on the same basic template, which is illustrated by the Corsair Air Series A70 tower we're installing. A back plate is affixed to the underside of the motherboard and then tied to the heatsink through the holes in the motherboard, either with screws or nuts on threaded posts. The fan—or fans, as is the case with the A70—are usually attached to the cooler separately, using plastic or metal clips.

Depending on the socket, you may be able to adjust the orientation of a tower-style cooler in 90- or 180-degree increments. Since the fan(s) generate airflow parallel to the motherboard, their orientation can have a big impact on airflow inside the case. The CPU fan should blow toward a chassis exhaust vent, usually found in the case's rear or top panels.

Fans typically indicate the direction of airflow with an arrow on the edge of the frame. In the picture above, the arrow on the right shows the airflow path. The arrow on the left points in the direction of the fan's rotation.

If the fan lacks a marker denoting the direction of airflow, there are other ways to figure it out. Most fans blow in the direction of the frame holding the rotor and its associated motor. The intake side is typically completely open or covered by a grill to prevent your fingers from getting munched by the blades. The direction of airflow can also be determined by looking at the shape of the blades, which push air out from their concave sides.