Cooling off the CPU – Attaching the CPU Cooling Fan

The computer processing unit, or CPU, is so dense with computer circuitry that as you try to run the chip faster and faster, it heats up hotter and hotter.  Any chip you purchase now comes with a CPU fan to help cool the chip down.  The cooler the chip, the faster it runs.  Seems like a paradox.  Cooler is faster, but if you run faster, it gets hotter.

With our last post we put the CPU into its socket on the motherboard.  Now we want to attach a fan directly to the CPU chip to cool it down.  You can use the CPU fan that came with the Core 2 Duo, or you may have purchased a separate cooling fan.  If you purchased a separate CPU fan, then you should have also purchased, some thermal compound.  I believe I recommended a brand called Artic Silver.

If you look at your motherboard, on the four sides of the LGA 775 socket are four holes through the motherboard where the CPU fan is mounted to the motherboard.  There are two ways commonly used to attach the CPU cooling fan to the CPU and motherboard.

The first method is used with the cheaper fans, and involves pushing posts with two barbs that look like arrow heads into each hole.  A pin is then pushed down between the two barbed ends to expand them in the hole.  The barbs catch on the underside of the hole and the fan is secured.  To remove the fan, you twist the pin up and out from between the two barbs, reach under the motherboard and squeeze the two barbs together and push it back through the hole on the motherboard.

Intel push down CPU fan

Intel push down CPU fan

This is the way the fan provided by Intel attaches to the motherboard.  I don't care for this method, because the barb and pins, which are made out of thin plastic, can easily tear and break.  What happens is one of the barbs breaks in the hole.  Once a barb breaks off, you can no longer attach that corner of the fan to the CPU.  You'll only have this happen once, and you'll quickly move to mounting method two, which involves purchasing a separate CPU fan.

The second method is much more secure.  It involves putting a screw through a hole in the fan mounting bracket, through the motherboard, and into a screw bracket you have placed under the motherboard.  It's like a sandwich, the two brackets have the motherboard in the middle.   The brackets have four holes in them that line up with the four holes on the motherboard.  You tighten the screws and the bracket is attached.  The fan then attaches to this bracket with two small screws.  To take off the fan, you unscrew the screws.

Third Party CPU fan

Third Party CPU fan. Bracket not shown.

The only problem with this second method is if you ever want to change your fan to a different one, with a different mounting set up, you will have to get to the bottom of the motherboard in the computer case.  That means unplugging everything and pulling out the motherboard.  A real pain, as you'll see as we start putting our computer together.  You pick your poison.  Since I usually don't switch fans, I prefer this method.

I'm going to assume you purchased a separate CPU cooling fan.  The one that comes from Intel is noisy, and barely gets the job done.  There are much more efficient and quieter CPU Cooling fans  out on the market.

Here we go.  Take the CPU cooling fan out of it's packaging.  Be careful with the fan and cooling fins that you don't bend them.   Carefully unwravel the power wire and plug from between the fan.  Before actually making any attachment, to see how everything will go together place the CPU Cooling fan on top of the CPU, and play with the mounting hardware until you understand how everything will attach together.  You have the square screw holder under the motherboard, the top bracket has a notch in it for the CPU latch to swing up, so the bracket should be lined up so the latch can be lifted.  You'll notice a separate bracket with two screw holes that attach the fan to the bracket attached to the motherboard.  Once you see how everything goes together,  take the fan part off, and attach the bracket to the motherboard with the four long screws.

We're ready for the thermal compound.  If your using Artic Silver, there is an instructional pdf on their web site on how to apply their thermal compound to the Core 2 Duo.  Read their instructions.  You only want to apply a thin bead in a line down the middle of the CPU and that's it.  The thermal compound will fill in the microscopic holes in the fan and CPU plates to form a good thermal transfer.  Too much compound is not good.

After you apply the thermal compound, put the fan base on the CPU and attach it with the second bracket.  Note, if your using the Intel fan, they have provided thermal compound on the bottom of the fan plate already.

You'll need to provide power to the fan.  Look around the LGA 775 socket for a white interface with four pins sticking up.  It should be labeled "CPU fan."  Attach the wire with the plug to the interface on the motherboard.  It only goes on in one direction.  Congratulations, the CPU cooling fan is all set up on the motherboard.

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