Apparently, there are digits in the marking of AMD Athlon XP “Thorougbred” CPUs that describe the speed this particular CPU was designed to work at but was later “downgraded” or maybe even “upgraded” in certain cases. Take a look at the example of how the Athlon XP “Thoroughbred” processors are marked:
According to the source, the seventh and eights marks in the second line of the sticker describes the initial speed the processor was designed for (RFBEXR2280073). If the initial model number is higher than the number you have, it means that your processor has been downgraded.
The owner of the web-site explains that “downgraded” in this case means that the CPU was not able to maintain full stability at the given rating with default voltage, so it was remarked to a lower model number. For example, 1700+ downgraded from 2400+ means that this CPU cannot work at 2400+ with core voltage 1.6V, but it can probably hit this and maybe even higher frequencies with voltage increase.
There are rumors that AMD re-stamped the markings of some high-speed CPUs to fulfill the huge demand for lower-speed ones (mostly 1700+ and 2100+), if this is your case, then the CPU should be able to work stable even at 2400+ with the default voltage.
