You must wonder why the Athlon XP does not allow working in a symmetrical multiprocessing configuration (more than one processor in the same computer). That is a doubt all hardware specialists had, especially because AMD had initially said that the Athlon XP would have support to multiprocessing. It seems that it gave the idea of having that resource in the Athlon XP at the last minute, making the symmetrical processing exclusive to the Athlon MP and the new Durons.
But the site HardwareZone (http://www.hardwarezone.com) discovered something extremely interesting: the Athlon XP and the Athlon MP are internally the same processor, the only difference being that in the Athlon XP the resource of symmetrical multiprocessing was disabled. And there is more: such disabling is done outside the processor, in one of the fuses in the body of the computer, and not internally.
That fuse is the last fuse of the L5 bridge. At the Athlon MP that fuse is closed, while at the Athlon XP that fuse is open. In other words, all you have to do is close the last fuse of the L5 bridge of the Athlon XP to transform it into an Athlon MP! At the site of the HardfwareZone we can see the various tests that were carried out and have proved that this solution works. That "closing" of the fuse should be done preferentially using a pen with conductive paint. That type of pen is used to repair printed-circuit boards and can be found at electronic parts stores. In case you do not have a pen like at hand, you can try connecting the fuse using a 2B pencil (That's right, a common pencil - lead is conductive).
In the sequence we show the pictures taken from the site of the HardwareZone, showing where the group of L5 fuses is located and which of the fuses you should connect in the Athlon XP to transform it into an Athlon MP. We remind you that this type of modification makes any warranty of the processor void, and we are not responsible for any damage you may cause to your equipment.
Figure 1: Where the group of the L5 fuses is located in an Athlon XP processor.
Figure 2: The fuse of the Athlon XP that should be closed to transform it into an Athlon MP.
Figure 3: Detail of the fuse of new Durons (Morgan core). The way it is connected allows the new Durons to work in multiprocessing.
Figure 4: Detail of the fuse of th Athlon XP connected with conductive paint.