Cache (three-level cache) is divided into two types, the early one is external, and the later upgraded products are built-in. Its practical function is that the application of L3 cache can further reduce the memory delay and improve the performance of the processor when computing large amounts of data. Reducing memory latency and improving the computing power of large data are very helpful to the game. However, there is still a significant improvement in performance by adding L3 cache in the server field. For example, a configuration with a larger L3 cache can use physical memory more efficiently, so it can handle more data requests than a slower disk I/O subsystem. Processors with larger L3 cache provide more efficient file system caching behavior and shorter message and processor queue length. In fact, the earliest L3 cache was applied to the K6-III processor released by AMD. At that time, L3 cache was not integrated into the chip, but integrated into the motherboard due to the manufacturing process. L3 cache, which can only synchronize with the system bus frequency, is not much different from main memory. Later, the L3 cache was the Itanium processor introduced by Intel for the server market. Then came P4EE and Xeon MP. Intel also plans to introduce an Itanium2 processor with 9MB L3 cache and a dual-core Itanium2 processor with 24MB L3 cache in the future. But basically L3 cache is not very important to improve the performance of the processor. For example, Xeon MP processor equipped with 1MB L3 cache is still no match for Opteron, which shows that the increase of front-end bus will bring more effective performance improvement than the increase of cache.