Cold Boot is hard to implement, and can be mitigated by putting the 16kb of key memory on the L2/L3 cache or some other piece of memory that instantly clears on

Cold Boot is hard to implement, and can be mitigated by putting the 16kb of key memory on the L2/L3 cache or some other piece of memory that instantly clears on power off. With FDE and memory encryption, how else can you get pass this?