Pentium-M vs. Pentium 4-M

This article compares the differences between the Pentium-M and Pentium 4-M. Both are great performing processors, but have certain differences which you should know about. It should also be noted that the Pentium-M does not refer to the first generation Pentium I processor. This is just the name Intel gave for this mobile processor.

The first difference between these two processors is clock speed. In general, you should never base a laptop's performance just on clock speed. This rule is very true in the case of these two processors. Even though the Pentium-M and Pentium 4-M have very different clock speeds, they actually can have very similar performance. The Pentium-M has a lower clock speed but has a higher IPC (instructions per cycle). In other words, it can do more work in less clock cycles. The Pentium-M was designed this way to minimize power consumption and maximize battery life. The Pentium 4-M is the opposite and performs at a much higher clock speed with less IPC. If you were to compare the two, a Pentium-M 1.6GHz is approximately equivalent to a Pentium 4-M 2.2GHz or Pentium 4-M 2.4GHz depending on what applications you are running. However, the Pentium 4-M particularly excels with multimedia related applications.

There are a few improvements in the Pentium-M which helps make up for its lower clock frequency. One of the technical improvements is the advanced branch prediction unit which had two additional predictors added, helping boost real world performance by up to 7% over the previous branch prediction architecture. Another improvement was the amount of cache memory. The Pentium 4-M is fitted with 512K L2 cache while the Pentium-M has 1MB L2 cache.

The decision over what type of processor to choose depends on the type of applications you expect to run. If you are into video encoding, playing 3D games or just want a desktop replacement, then choosing a high frequency Pentium 4-M may be a better choice. If long battery life is most important, then go with a Pentium-M based laptop.