Final answer:
The memory cache that is closest to the processor die but not housed on the die is called L3 cache. It is larger but slower than the L1 and L2 caches and is typically located outside the processor die but still in close proximity.
Step-by-step explanation:
The cache memory that is closest to the processor die but is not housed on the die is called L3 cache.
When the processor needs data or instructions, it first checks the L1 cache which is the smallest and fastest cache, located directly on the processor die. If the data is not found in the L1 cache, the processor checks the L2 cache, which is larger but slower than the L1 cache. Finally, if the data is not found in the L2 cache, the processor checks the L3 cache which is the largest but slower than the L1 and L2 caches, and is typically located outside the processor die but still in close proximity.
The purpose of having multiple levels of cache is to reduce the time it takes for the processor to access frequently used data, as accessing data from cache is faster than accessing it from main memory.