The finer distinctions between DDR and GDDR can easily be masked by the impressive on-paper specs of the newer GDDR5 standards, often inviting an obvious question with a not-so-obvious answer: Why can’t GDDR5 serve as system memory? In a simple response, it’s analogous to why a GPU cannot suffice as a CPU. Being more incisive, CPUs are comprised of complex cores using complex instruction sets in addition to on-die cache and integrated graphics. This makes the CPU suitable for the multitude of latency sensitive tasks often beset upon it; however, that aptness comes at a cost—a cost paid in silicon. Conversely, GPUs can apportion more chip space by using simpler, reduced-instruction-set based cores. As such, GPUs can feature hundreds, if not thousands of cores designed to process huge amounts of data in parallel. Whereas CPUs are optimized to process tasks in a serial/sequential manner with as little latency as possible, GPUs have a parallel architecture and are optimized for raw throughput. While the above doesn’t exactly explicate any differences between DDR and GDDR, the analogy is fitting. CPUs and GPUs both have access to temporary pools of memory, and just like both processors are highly specialized in how they handle data and workloads, so too is their associated memory.