CPU vs. GPU Rendering: Which Is Best for Your Studio Projects?

High-definition image processing is the life-blood of today’s VFX, graphic design, industrial design, and animation industries. When working in one of these industries, the most important tool in your arsenal is your workstation. The Central Processing Unit (CPU) is the heart of your workstation and handles a lot of tasks, like executing applications, loading drivers, etc. Graphics Processing Units (GPUs), which are specialized types of microprocessors that run parallel to the CPU, have recently seen a significant rise in usage as massive calculations that are needed for a single task begin to grow. These processor-intensive tasks may include:

• Gaming
• 3D visualization
• Visual effects
• Image processing
• Big data
• Deep learning / AI

For the sake of not overcomplicating this article or its purpose, we’ll be exclusively referring to comparing CPUs and GPUs used for image processing, or in this case, image rendering. Hopefully after reading this, you will have a better, more comprehensive understanding of what these types of rendering solutions can offer you and your studio and assist you in making a more educated decision as to what is a better option for your projects.

CPU Rendered Result	GPU Rendered Result

CPU vs. GPU Speed

The first and most obvious factor to address is speed. While a CPU has a limited number of processing cores (averaging at around 24) that make it efficient at sequential serial computing and carrying out processes one at a time, GPUs consist of smaller cores in greater quantity than that of an average CPU, allowing your workstation to perform multiple tasks at the same time much more quickly.

Modern GPUs have increased in their output capabilities since they were first introduced. Where CPUs generally are able to handle individual specific tasks in sequence, GPUs offer superior memory bandwidth, processing power, and speeds up to 100 times faster to tackle several tasks that require multiple parallel computations and large caches of data. 

Hours of processing can be displayed in minutes and can streamline the design process when using GPUs. If speed is the main priority in your workflow, GPU-based rendering is the preferred solution.

CPU Render Time (18.4 minutes)	GPU Render Time (6.5 minutes)

CPU vs. GPU Initial Graphic Fidelity

Rendering is a time-consuming process, but quality can’t be rushed. Though it might take hours (maybe even days) to finish rendering an image, traditional CPU-based rendering is more likely to deliver higher image quality and much clearer images that are devoid of noise.

A GPU has many more cores than a CPU, but overall, each core runs slower compared to a CPU core. When several CPUs are interconnected and put to use in a render farm-like environment, for example, they can potentially produce a more exquisite final result than a GPU-based graphics solution could. In film, this is the usual standard for producing high-quality frames and images as there is no hard limit to rendering. 

On the other hand, with affordable VR on the rise, games are also becoming much more immersive, and with immersion comes high-quality image rendering and real-time processing that can put a workstation to the test. To put it simply, modern games and VFX are just too taxing for a CPU graphics solution anymore.

If you’re willing to take your time and aren’t pressured by deadlines to get the very best possible image, then CPU-based rendering may be what you’re looking for.

CPU Rendered Result (Intel i7)	GPU Rendered Result (Nvidia CUDA GPU)

CPU vs. GPU Cost

As hardware becomes more impressive, its price also becomes a deciding factor. 

In addition to speed, the power of a single GPU can be the equivalent of at least five to ten CPUs. This means the power of a single workstation can perform the tasks of several CPU-based workstations put together allowing independent artists and studios the freedom to create, design, and develop high resolution images at home. Furthermore, GPUs offer a significant decrease in hardware costs and eliminate the need for multiple machines to produce professional quality work that can now be made in minutes instead of hours.

Without the need for expensive CPU render farms, individual creators can afford and rely on their own GPU workstations and have studio-quality work for a fraction of the cost.

CPU vs. GPU Real Time Visualization

With certain workflows, particularly VFX, graphic design, and animation, it takes a lot of time to set up a scene and manipulate lighting, which usually takes place in a software’s viewport. A workstation’s GPU can drive viewport performance in your studio’s software, allowing for real time viewing and manipulation of your models, lights, and framing in three dimensions. Some GPU-exclusive rendering software can even allow you to work completely in a rendered viewport, increasing your output and minimizing potential errors that may arise from rendering in another program.

It’s very clear to see the benefits of working and rendering with GPU-accelerated machines compared to the traditional CPU-based workstations that can slow down production or limit project budgets due to potentially necessary upgrades.

Making the Choice Between CPU and GPU Rendering

Keep in mind that GPUs aren’t intended to completely replace the need for CPU workstations and workflow. It may appear that the benefits of CPU-based rendering pale in comparison to the benefits of GPU-based rendering, but it ultimately depends on what you or your studio need. These processing units live and operate in a synergistic harmony. The GPU is not to replace, but to accelerate and streamline existing practices and workflows, maximize output, and offset processor-heavy computations in applications that would bog down a system without them.

Even with the fastest, most powerful GPUs at your disposal, the CPU is still pulling its share of the weight. To the untrained user, it will just appear that your applications run much faster and smoother. Using these tools in tandem will do so much more for your work and presentations, and greatly increase your machine’s ability to quickly bring your creations to life. Happy Rendering!