Taken from
quietpcUSA.com
1. Remove the old bracket, fan and heatsink
Firstly, if you are building a PC from scratch rather than replacing the noisy cooler on a PC which is already built, please skip straight to step 3.
Otherwise, unplug all cables from the PC and place it on a clean work surface with plenty of room for manoeuvre. Remove the cover. If access space around the CPU is tight, you should remove the motherboard entirely from the case and place it on a flat working surface, preferably on top of an anti-static bag or mat. Do not work on a carpet, (especially not a carpet containing nylon), as static electricity can damage electronic components. We recommend you wear an anti-static wristband or take other proven anti-static protection measures.
Disconnect the existing CPU fan connector from the motherboard, making a note of where it went. The procedure for removing the existing cooler will vary slightly depending on the exact type of cooler installed. Most of the Pentium 4 coolers have 4 distinct parts: a bracket (which clips onto a base frame), a fan, a heatsink and a plastic base frame (fixed to the motherboard with pushpins). Generally, the bracket also has 2 pressure levers that push down the fan and the heatsink onto the Pentium processor.
First, you must unlock the 2 pressure levers that are sitting atop the bracket by lifting up each of the levers. Once this has been done, the bracket, the fan and the heatsink can be moved. The next thing you must do is to release the 4 clips that are holding the bracket to the plastic base frame which is fixed to the motherboard. To do this, you need to slip a small screw driver under each of the bracket clips and push the clip outward and away from the plastic base frame so that the clip becomes disengaged. A slight upward force on the bracket at the same time will help disengaged the bracket clip. Once all 4 clips have been disengaged, you can remove the bracket, the fan and the heatsink. You will now be looking at the plastic base frame attached to the motherboard.
2. Remove the plastic base frame
To remove the plastic base frame, you must first GENTLY remove each of the push pin rods that have been inserted into the pushpin sleeves in each 4 corners of the bracket. To do this, insert a small screwdriver under the head of each of the pushpin rods and pry in up slightly. Be careful not to behead the pushpin rod. If you accidentally cut off the head of the pushpin rod, it will be very difficult to remove rod thereafter. Once the pushpin rod begins to move, taking out the rod should be easy. Remove all 4 pushpin rods. Once this has been done, the plastic base frame will still be attached to the motherboard but the pushpin sleeves can now be compressed because the rods are no longer in the sleeves. GENTLY pull up each corner of the plastic base frame to disengage each pushpin sleeve from the motherboard. Each of the pushpin sleeves should POP out of the motherboard hole. DO NOT place any screw driver under the plastic base frame for better leverage in removing the plastic base frame. There are delicate tiny resistors in this area of the motherboard and they can be damaged. If they become damaged, you will need to buy a new motherboard.
3. Prepare the processor
Ensure that the CPU is firmly installed in its socket as shown. Do NOT power up the PC at this point! The CPU would overheat and be completely destroyed within a few seconds. The next stage is to ensure that the raised core of the CPU (also called the die) is completely clean and free of any thermal paste or the remains of any thermal interface pad. If your CPU has not previously had a cooler installed, then cleaning the die will not be necessary. Otherwise, you should use a cotton bud or lint-free cloth, and a low residual solvent such as iso-propyl alcohol or acetone (nail polish remover). Before proceeding you must ensure that the CPU core is entirely free from heatsink compound, fingerprints, dust, hairs etc. For a good thermal connection, the surface of the CPU core must be 100% clean.
4. Attach the Molex metal frame to the motherboard
Place the Molex metal frame over the holes on the motherboard. Make sure that the Molex metal frame has the fan guides facing up so that the new CPU cooler does not move when place on top of the frame. Take the first of the 4 pushpins and remove the pushpin rod from the pushpin. Insert the pushpin sleeve (without the rod) into one of the holes and push it down until it SNAPS into the motherboard. Once this has been done, take the pushpin rod and insert it into the pushpin sleeve until it goes down all of the way. Once the pushpin rod had been inserted into the pushpin sleeve, the pushpin can no longer be removed from the motherboard. Repeat the above procedure for the each of the other holes on the Molex metal frame using the other 3 pushpins. Once this has been done, the new Molex metal frame should be firmly attached to the motherboard.
5. Install the new CPU cooler
Now it is time for action! Remove the green protective cover from the thermal interface pad on the new CPU cooler. Carefully, place the new CPU cooler on top of the Molex metal frame so that the holes on the cooler correspond to the holes on the Molex frame. The thermal interface pad should be in contact with the Pentium 4 processor. Insert the 2 screws in to the holes on the CPU cooler and screw them into the Molex metal frame until the screws are most of the way down and that there is good pressure applied by the springs.
6. Final installation
Well done! All you need to do next is to plug the fan connector into the motherboard. Your motherboard and CPU represent delicate electronic components. Every effort must be taken to make sure that you are aware of what you are doing and follow these instructions carefully. Your efforts will be more than worthwhile, and your PC will be much quieter for years to come!
-----------------------------------------------------------------------------------
If you've installed the HSF and CPU yourself, the steps to remove the CPU and HSF would be performed in
reverse to how they were initially installed
If you purchased your computer (that is, you did not custom build it), then the aformentioned steps will be applicable to your situation