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PII Disassembly




With the introduction of the Pentium II and the S.E.C. Cartridge Processors we now have a CPU on a card. In the past opening up your CPU meant risking total destruction just to look at a little IC with tiny gold threads coming off it. An example of this is the Cyrix CX486DX40. Now we can't go this far with a Pentium II since they still have some value (even the older ones) but we can take a look at the parts that make up the Pentium II CPU.

    Since Intel doesn't like people messing with their processors attempting to duplicate the following procedure will void your warranty big time! Operating your CPU at anything other than the specs as laid out by Intel will void your warranty, this includes overclocking the CPU or the system bus, higher or lower voltage, overheating or supercooling or using an improper heat sink. Cursing Intel under your breath may also void your warranty and posting anything negative about Intel or making fun of Intel or using a typewriter that drops the 'e' is frowned upon by the mighty Intel.

    This is the last time you will be reminded that attempting disassembly will void your warranty, Intel will know you have tried and will not be interested in what ever problems your CPU has. There is also a very real possibility that you will damage or destroy your PII in attempting these procedures. You should take antistatic precautions and do this work on a well lit bench. Generally speaking you shouldn't do most of the stuff I do, or you should at least be prepared to accept the consequences.

    In fact due to the nature of the SLOT 1 and S.E.C. connector removing your CPU from your motherboard is a bad idea. The high speeds (what we call high speeds for now) that the SLOT 1 is dealing with means it is best to leave your CPU in the slot. Just like the old cache cards, removing and reinstalling repeatedly will cause contact problems which you don't want. Of course like the cache cards taking it out once or twice won't be a problem.

A boxed Pentium II 266 CPU was used for these procedure.

Glossary of terms

Procedure:

    This procedure is for removing or accessing the processor substrate or Thermal Plate. Non-Traditional cooling methods may require full access to the thermal plate especially if drilling or tapping is required.

- Removing the PII from the motherboard requires disconnecting the fan and sliding the clips on the heat sink support towards the CPU. They should click when clear. Lift one end of the processor until it clears the connector, then lift the other end. Sometimes wiggling the CPU by lifting one end a bit and then the other will make the removal less stressful on the motherboard.

 

Fanoff.JPG (31421 bytes)Remove the heatsink fan and plastic housing. You will be using the heatsink to hold the CPU during this procedure. Removing the fan prevents its damage. It is held on at four points which slide under the top and bottom edge of the heat sink. A small screw driver can be used to push the plastic down and back if finger power alone doesn't do it.

 

 

The next and difficult step is removing the cover.

covbk.JPG (33136 bytes) This image shows the back side of the cover with arrows pointing to the attachment points. These are the four points that slide over pins attached to the Thermal plate. These  are square holes which slide over a rounded pin so they are really well seated.

 

- I pried the side of the cover up and out a bit with a small screw driver until I could get a larger sized flat bladed in. Then twisted the screw driver to pry the cover away from the thermal plate. It is important to not touch or stress the substrate.

- Pressure should be between the thermal plate and the cover only. The latch arms will get in the way of this procedure but you can work around them. The latch arms can be removed with the cover. The left latch arm is shown separate from the cover in the pic. The right Latch arm is in place.

- You could hold the heat sink in a vise for this work but it could be bent. The thermal plate is made of 6063-T6 Aluminum and the heat sink seems to be much softer stuff than that so I didn't like the vise idea. I felt better holding it in my hand so I always knew how much force was being applied.

- Once I had one edge up I just held on to the edges of the cover and pulled and wiggled, and pulled and wiggled. Once it gets going it's not too bad.

    If I was going to do this again I would consider applying heat to the front of the cover in the areas of attachment. The cover is made of GE Lexan 940 and if this is like other Lexan material there is a temperature at which it will become softer yet not melt. So you should be able to retain the nice mat finish on the cover, and leave little evidence of tampering. The GE specs on this material should let you know if this is possible.

Now that you have the cover off, take a rest because the next step may not be as difficult but will be riskier.

covoff.JPG (49751 bytes) This image shows the PII with cover removed. The only things holding or attaching the substrate to the thermal plate are two Thermal Plate Attach Clips. They have been pressed into place over the thermal plate pins. To remove them you will have to bend back at least 2 of the 'fingers' that are touching the pin.

 

- I used a small pair of electronic pliers to bend the 'fingers' back away from the pin.

- As in all of this procedure hold on to the thermal plate and don't stress the substrate.

- Since this is work is right up against the substrate, don't slip and scratch the circuit board. I would suggest putting at least a piece of paper on the board to prevent any contact.

- Once you get the 'finger' clear of the pin it will want to spring up pretty quick, be ready for it and keep it under control.

Clip2.JPG (9615 bytes)This image shows the Thermal Plate Attach Clips removed. The top one is showing the side that contacts the circuit board. There is a layer of plastic that prevents the metal clip from shorting out or rubbing the tracings on the substrate.


             Intel may have  a problem with the installation of these clips. One of my attach clips popped off during a gentle (I mean very gentle) exploratory wiggle. This released the pressure off the substrate.  This could allow the thermal plate to move away from the processor, which would result in a poor thermal contact. The cover can help hold the substrate to the thermal plate but it would be a poor replacement for a properly installed clip. This was not related to the work I had done up to this point as the substrate had seen little or no direct pressure and even if it had, a properly attached clip would have held.

clip1a.JPG (10476 bytes) This shot isn't very clear but it was taken right after the cover was removed and before I had started to remove the clips. Click on image for a larger picture (40K) and you can make out that the clip on the right side is secure with one 'finger' down under the pin lip. Only one 'finger' is required for a secure connection. The clip connection on the left side of picture shows that neither 'finger' is well below the lip and both appear to be resting on the head of the pin. This is the problem. At least one 'finger' should be below the lip.

NoHS2.JPG (12096 bytes) Removing the the boxed heat sink will require a 1.5mm Allen wrench (or key). The key will slide through the 'Rivscrew' right down to the substrate. It is ok to touch (gently) the substrate with the key but do not contact the substrate when turning the key. Rivscrew is actually a removable rivet. Each one is threaded and the hole is 'threaded' when the rivet is installed. Due to this process each threaded hole is unique. If you plan to reuse the rivscrews (not recommended) try to get them back in the same hole they came from. If you have removed the substrate from the thermal plate then the rivscrews can be drilled out like a regular rivet. Try removing them with an Allen key first. The holes can be tapped with a 6-32 tap.

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