What is external cache?
An external cache is any cache or type of central processing unit (CPU) cache that is housed, placed, or installed outside of a computer processor.
It provides high speed data storage and processing services for the computer processor, its primary / native cache and main memory. External cache is also known as the secondary cache.
External cache is part of main memory (RAM) or an independent component that is installed on the motherboard. Some external caches are built and integrated on the processor dye itself, but not directly that part of it.
It serves as a buffer between the processor and RAM. The external cache is implemented in several layers - each offering different speeds and capacity levels. For example, L2 and L3 caches are common examples or layers of external cache. An L2 cache is faster, but has less storage capacity than an L3 cache.