What does an RT Core do?

An RT Core accelerates the mathematical calculations needed for real-time ray tracing. It specifically handles bounding volume hierarchy traversal and ray-triangle intersection tests, freeing up main shaders for other graphics tasks.

Can you run ray tracing without RT Cores?

Yes, graphics cards without dedicated hardware can emulate ray tracing through software compute shaders. However, this approach causes severe performance drops, making games virtually unplayable.

Do AMD graphics cards have RT Cores?

AMD graphics cards use a similar specialized hardware component called Ray Accelerators. Starting with the Radeon RX 6000 series, these units perform the same fundamental tasks as Nvidia RT Cores.

Do RT Cores improve non-ray-traced gaming performance?

No, RT Cores remain idle during traditional rasterized games. They do not boost frame rates unless you enable ray tracing features within the game settings menu.

What is the difference between an RT Core and a Tensor Core?

RT Cores calculate light ray interactions and geometry intersections. Tensor Cores handle deep learning matrix multiplication used for AI tasks like DLSS upscaling and image processing.

What are RT Cores? Ray Tracing Hardware Explained

What is an RT Core?

An RT Core (Ray Tracing Core) is a dedicated physical hardware unit found on modern graphics processing units (GPUs), designed specifically to accelerate the computationally intensive math required for real-time ray tracing. It calculates how light rays interact with virtual environments, enabling realistic reflections, shadows, and lighting in video games and professional rendering applications.

Key Takeaways

RT Cores are specialized hardware accelerators distinct from standard shading units.
They offload the massive mathematical burden of bounding volume hierarchy (BVH) calculations.
Without dedicated cores, real-time ray tracing severely degrades gaming frame rates.
First introduced by Nvidia in 2018, they are now standard in modern desktop and console GPUs.

History and Evolution

Before dedicated hardware, real-time ray tracing was a holy grail for computer graphics. Standard GPUs relied entirely on rasterization—a technique that projects 3D models onto a 2D screen but struggles with accurate light bounces.

In 2018, Nvidia introduced the Turing architecture, featuring the first generation of RT Cores inside GeForce RTX GPUs. AMD followed in 2020 with Ray Accelerators in their RDNA 2 architecture. Today, multi-generational advancements have drastically increased the number of ray-triangle intersections a GPU can calculate per clock cycle.

How RT Cores Work

Ray tracing simulates the physical behavior of light by casting millions of virtual rays from the camera viewpoint back into the 3D scene. To do this efficiently, hardware uses a spatial sorting structure called Bounding Volume Hierarchy (BVH). The RT Core handles two primary workloads:

BVH Box Traversal

The core tests rays against large virtual boxes encompassing groups of 3D objects, continuously narrowing down the location of an object until it finds a match.

Ray Triangle Intersection

Once the correct box is identified, the core calculates the exact point where the light ray intersects with the polygon triangles of a 3D model.

By offloading these two geometric math operations, the primary graphics shaders are freed up to handle pixel shading; frame rates stay playable, and lighting updates in real time.

RT Cores vs. Traditional Shaders

Feature	RT Cores	Traditional Shaders (CUDA / Stream Processors)
Primary Function	BVH traversal and ray intersection math	General geometry, pixel, and vertex shading
Workload Type	Highly specialized bounding box calculations	General-purpose parallel computing
Ray Tracing Speed	Extremely fast due to dedicated hardware pipelines	Very slow when forced to emulate ray equations
Versatility	Fixed-function architecture	Highly programmable for various graphic tasks

Advantages of Dedicated Ray Tracing Hardware

Photorealistic Visuals

Enables physically accurate global illumination, ambient occlusion, soft shadows, and lifelike reflections that adapt dynamically to moving objects.

Frame Rate Preservation

Offloading ray calculations prevents the primary GPU shading processors from becoming bottlenecked, ensuring smoother gameplay.

Dynamic Environmental Scaling

Allows developers to build open worlds where lighting changes realistically based on time of day, weather, and player actions without pre-baking lightmaps.

Limitations and Challenges

Performance Overhead

Even with dedicated hardware, enabling ray tracing causes a noticeable drop in frames per second, often requiring AI upscaling tools like DLSS or FSR to compensate.

Silicon Die Space

RT Cores occupy physical space on the GPU chip, which increases manufacturing costs and power consumption.

Software Dependency

The hardware remains idle if a video game or rendering application does not explicitly support modern ray tracing APIs like DirectX Raytracing (DXR) or Vulkan.

Related Technology Terms

Rasterization: The traditional method of rendering 3D graphics by translating vector data into pixels.
BVH (Bounding Volume Hierarchy): A tree structure used to organize geometric objects to optimize ray tracing calculations.
Path Tracing: An advanced form of ray tracing that simulates thousands of light rays per pixel for ultimate graphical fidelity.
DLSS (Deep Learning Super Sampling): Nvidia AI technology that upscales lower-resolution frames to offset the performance cost of ray tracing.

RT Cores

Definition