As with the earlier P3-450, the P3-500 includes all of the major upgrades that the "Pentium(r) 3" moniker brought to the market at the time of its release. These improvements over the Pentium(r) 2 line are as follows: (as paraphrased from Sharky Extreme's earlier P3-450 review)

The specifications on the P3-450 match the Pentium(r) 2-450 CPU it's meant to replace for the most part, with two notable exceptions:

The P3's SECC2 cartridge format, and 70 new SIMD instructions designed to aid software developers in accelerating the already-competent floating point unit the Pentium(r) 3 is equipped with.

SECC2, or Single Edge Contact Cartridge, is the term that Intel(r) uses to describe the P3's "topless" case design. Much like the Intel(r) Celeron(tm) CPU product line, the Pentium(r) III allows a heatsink/fan to come into direct contact with the CPU's core. This wasn't possible previously with the Pentium(r) 2 CPU line, with its fully enclosed SECC format.

During heat monitoring tests we found that the SECC2 design serves the P3 well, it operated at a lower temperature than a standard P2-450 CPU while running identical benchmarks in an identical machine. The heat reduction wasn't spectacular, but it was tangible (about 5 degrees Celsius lower).

We observed similar results in regards to heat with the two P3-500s we tested the past two weeks, they both held to lower temperatures than the P2-450 CPUs we've utilized.