In terms of overall gaming performance, the Intel Pentium 4 Mobile M2.5GHz is marginally better than the Intel Pentium 4 Mobile 2.8GHz when it comes to running the latest games. This also means it will be less likely to bottleneck more powerful GPUs, allowing them to achieve more of their gaming performance potential.

The Mobile 2.8GHz was released over a year more recently than the Mobile M2.5GHz, and so the Mobile 2.8GHz is likely to have better levels of support, and will be more optimized for running the latest games.

Both CPUs exhibit very poor performance, so rather than upgrading from one to the other you should consider looking at more powerful CPUs. Neither of these will be able to run the latest games in any playable way.

The Mobile 2.8GHz and the Mobile M2.5GHz both have 1 cores, and so are quite likely to struggle with the latest games, or at least bottleneck high-end graphics cards when running them. With a decent accompanying GPU, the Mobile 2.8GHz and the Mobile M2.5GHz may still be able to run slightly older games fairly effectively.

More important for gaming than the number of cores and threads is the clock rate. Problematically, unless the two CPUs are from the same family, this can only serve as a general guide and nothing like an exact comparison, because the clock cycles per instruction (CPI) will vary so much.

The Mobile 2.8GHz and Mobile M2.5GHz are not from the same family of CPUs, so their clock speeds are by no means directly comparable. Bear in mind, then, that while the Mobile 2.8GHz has a 0.3 GHz faster frequency, this is not always an indicator that it will be superior in performance, despite frequency being crucial when trying to avoid GPU bottlenecking. As such, we need to look elsewhere for more reliable comparisons.

Aside from the clock rate, the next-most important CPU features for PC game performance are L2 and L3 cache size. Faster than RAM, the more cache available, the more data that can be stored for lightning-fast retrieval. L1 Cache is not usually an issue anymore for gaming, with most high-end CPUs eking out about the same L1 performance, and L2 is more important than L3 - but L3 is still important if you want to reach the highest levels of performance. Bear in mind that although it is better to have a larger cache, the larger it is, the higher the latency, so a balance has to be struck.

The Mobile 2.8GHz has a 512 KB bigger L2 cache than the Mobile M2.5GHz, but neither of the CPUs have L3 caches, so the Mobile 2.8GHz wins out in this area with its larger L2 cache.

The maximum Thermal Design Power is the power in Watts that the CPU will consume in the worst case scenario. The lithography is the semiconductor manufacturing technology being used to create the CPU - the smaller this is, the more transistors that can be fit into the CPU, and the closer the connections. For both the lithography and the TDP, it is the lower the better, because a lower number means a lower amount of power is necessary to run the CPU, and consequently a lower amount of heat is produced.

The Mobile M2.5GHz has a 53 Watt lower Maximum TDP than the Mobile 2.8GHz. However, the Mobile 2.8GHz was created with a 40 nm smaller manufacturing technology. Overall, by taking both into account, the Mobile 2.8GHz is likely the CPU with the lower heat production and power requirements, by quite a wide margin.