The internal cache built into the 486 and Pentium CPUs ranges from 8K to 16K. This memory is able to keep up with the CPU's requests at the CPU's speed and greatly outperforms the external cache.

The external cache is the cache on the motherboard and ranges from 256K to 512K. At 20Ns or less, you can see that it is much faster than RAM at 70Ns or more. However it can not keep up to the CPU's internal cache.

So what does this mean? On 486 and above systems, data can travel from RAM to external cache on the motherboard to the internal cache in the CPU. All in all, it greatly improves processing.