Unlike previous eDRAM implementations in game consoles, Crystalwell is true 4th level cache in the memory hierarchy. It acts as a victim buffer to the L3 cache, meaning anything evicted from L3 cache immediately goes into the L4 cache. Both CPU and GPU requests are cached. The cache can dynamically allocate its partitioning between CPU and GPU use. If you donít use the GPU at all (e.g. discrete GPU installed), Crystalwell will still work on caching CPU requests. Thatís right, Haswell CPUs equipped with Crystalwell effectively have a 128MB L4 cache.