How to Balance a CPU and a GPUby Micah McDunnigan
While you could simply buy the most expensive high-end CPUs and GPUs for your computer, you don't necessarily have to spend a lot of money to get the most out of your computer system. In addition, balancing your CPU and GPU isn't as much of a concern as you may think, and largely comes down to how much money you want to spend and how you want to use your computer.
The idea of balancing your CPU and GPU concerns bottlingnecking, or when one component is preventing another component from performing to its full potential. For example, if you have an incredibly high-powered graphics card and a mediocre CPU, then the graphics card could be finishing its work faster than the CPU can accept that work and issue the GPU more. At this point, even if you install a better graphics card, your computer's performance isn't going to improve because your CPU is at the limit of what it can do with graphics cards. The same applies to having an incredibly high-powered CPU that starts issuing tasks to the GPU faster than the graphics card can handle them.
Different Applications, Different Loads
Balancing a CPU or GPU is not a straightforward proposition. While the distribution of labor between the two components is hypothetically simple, in reality every program taxes the two components differently. For example, office productivity software uses the CPU almost exclusively, leaving only light rendering work to the graphics card. Some video games can tax the graphics card far more than the CPU, while other games that have substantial AI components that place a heavy tax on both the CPU and GPU. The distribution of labor for one program can turn the CPU into a bottleneck on your computer, while another can turn your GPU into the bottleneck.
The CPU and GPU don't work together in a vacuum. For example, if you add more RAM to your computer, then your CPU can run faster. Having a high-end cooling system for your CPU can also allow it to reach higher speeds, and having better overall case cooling can help the performance of both the CPU and GPU. Even the specific motherboard model you use can affect how the two components perform.
Buy for What You Need
You can't know how a given hardware configuration will perform with any particular application until you actually run it, so attempting to perfectly balance your hardware is not possible. In general, you have to be pairing a very old CPU with a very new and very high-end graphics card for the CPU to become a bottleneck on a regular basis. As long as your computer's power supply unit generates sufficient wattage to support it, and you have a processor that isn't more than about three years old, you can generally just buy the level of graphics card you think you'll need.