its not designed to be opened. You should NOT re-paste these processors unless you are having an issue. That said, the SECC2 processors usually have that shitty paste with CLOTH between the die and heatsink. Its absolutely trash, and that should be replaced 100%.
You /can/ do it, and its fairly straightforward. you will need the following: (for non SECC2)
1 - small socket with a nut-driver. I personally use a 1/4" drive screwdriver and a ~10mm socket. you want something with a nice handle for control.
2 - You will also need a small flat-head screwdriver.
3 - a thin metal pry tool. A guitar pick can also work, but the metal shim type works better.
4 - standard paste/alcohol stuff
Using the thin pry tool, you can wedge it between the aluminum plate and the plastic shell. is just a press-fit onto the PCB. Each corner has a plastic stud and they can be wedged open if you are careful. The CPU is held to the aluminum heat-spreader with 2 clips on 4 studs. You can CAREFULLY unbend the tiny fingers holding the clips to the metal studs, until the clip can be removed. I personally have tiny flat head screwdriver for eyeglasses that I use for this.
Repaste as normal.
To re-attach the heatsink,
1. flatten the fingers back into place. It should make a nice 'H' in each end. It doesn't need to be perfectly flat, as the less you fuck around with these metal clips, the better. There is some capton tape on the middle of these clips. it needs to stay in place. if it falls off or is removed, it needs to be replaced. Capton tape is preferred, electrical tape is #2.
2. place the socket over the 'H' and press it back onto the stud. You want to avoid using too much force as you can gouge the PCB. This is bad. You use a socket so the stud goes into it. Again, the less the mess with these metal fingers, the better. You only need 1 per side to be under the tip of the stud. It's okay to get all the fingers under the lip of the stud, but its not required.
3. repeat for all 4 end of the 2 clips. The less you mess with these clips, the better.
4. the plastic should press back into place.
AMD slot-A and slot-2 Xeon all work in an identical fashion.
if you are talking about the SECC2 heatsinks, they are almost always plastic studs that just press fit into the back plastic. They work the same as zip ties. I've NEVER been able to remove these plastic clips and have them be re-useable. I'd plan to replace the plastic with screws/springs.
It is a mistake to think you can solve any major problems just with potatoes.
