A backside bus is an internal bus that connects the central processing unit (CPU) with cache memory such as level 2 (L2) and level 3 (L3) cache.
There are two types of buses that work to bring data up and down from a computer’s CPU. These are the front side bus and backside bus. By the way, it is surprising that there is no correlation between these two.
The front side bus carries data between the CPU and memory, the backside bus transfers data to and from the computer’s secondary cache.
Secondary or L2 cache stores the functions frequently used (repeatedly), and other data are closer to the processor. This allows the computer’s CPU to work more efficiently because it makes processes repeat faster.
When the processor needs information from the L2 cache, it is sent through the backside bus. Since this process needs to be extremely fast, the clock speed of the backside bus cannot afford to be left behind. This is why the backside bus is also as fast as the processor. At the same time, the speed of the frontside bus is very slow, so it is half the speed of the processor.