In terms of overall gaming performance, the AMD Phenom II X4 955 Black Edition is massively better than the AMD Phenom 9600 Quad-Core Black Edition 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 Phenom II X4 was released less than a year after the Phenom 9600 Quad-Core, and so they are likely to have similar levels of support, and similarly optimized performance when running the latest games.

The Phenom 9600 Quad-Core and the Phenom II X4 both have 4 cores, which is not likely to be a limiting factor for gaming.

Both the AMD Phenom 9600 Quad-Core Black Edition and the AMD Phenom II X4 955 Black Edition have the same number of threads. Both CPUs have one thread per physical core.

Multiple threads are useful for improving the performance of multi-threaded applications. Additional cores and their accompanying thread will always be beneficial for multi-threaded applications. Hyperthreading will be beneficial for applications optimized for it, but it may slow others down. For games, the number of threads is largely irrelevant, as long as you have at least 2 cores (preferably 4), and hyperthreading can sometimes even hit performance.

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 Phenom 9600 Quad-Core and Phenom II X4 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 Phenom II X4 has a 0.9 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. In this case, however, the difference is probably a good indicator that the is superior.

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 Phenom 9600 Quad-Core has a 2044 KB bigger L2 cache than the Phenom II X4, but on the other hand, it is the Phenom II X4 that has a 4 MB bigger L3 cache than the Phenom 9600 Quad-Core. The L3 size of the Phenom 9600 Quad-Core is probably low enough to greatly inhibit its gaming performance in comparison to the Phenom II X4.

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 Phenom 9600 Quad-Core has a 5 Watt lower Maximum TDP than the Phenom II X4. However, the Phenom II X4 was created with a 20 nm smaller manufacturing technology. Overall, by taking both into account, the Phenom II X4 is likely the CPU with the lower heat production and power requirements, by quite a wide margin.