Since the day Sempron CPU from AMD was released one of the most frequently asked question is "afterall, what is the difference between Sempron and Athlon XP?"

Sempron is a slower Athlon XP (the exception goes to the Sempron socket 754 versions, which are an Athlon 64 with less L2 memory cache; these models use socket 754 pinout, thus requiring motherboards originally developed to Athlon 64, having a greater performance then socket 462 models). Originally Sempron socket 754 didn't have the 64-bit extensions available on Athlon 64, but since July, 2005, AMD introduced the 64-bit instructions on these processors. So, the socket 754 Semprons listed below can be found with or without the 64-bit extensions.  The models with 64-bit extensions enabled have the letters "BX" as the two last letters printed on the CPU package.

The difference in performance between Sempron and Athlon XP occurs due to the numbering system used to designate the processor's speed, which is differente for each processor. A Sempron 3000+ isn't faster than an Athlon XP 2800+, even though it has a greater number. The processor numbers can only be used to compare CPUs in the same product line, i.e. you can only compare Sempron to Sempron and Athlon XP to Athlon XP.

To fully understand this issue, take a look on the tables below. As you can see, a Sempron 2800+ is slower than an Athlon XP 2600+ 333 and a Sempron 2600+ is slower than an Athlon XP 2500+. To make the comparison, you have to watch the internal clock, the external clock and the L2 memory cache size.

This naming scheme used by AMD is really confusing. As you can see there are three Athlon XP 2600+ models with completely different technical specs, even though they use the same name.