Ray Tracing: What It Is and How It Works

What Ray Tracing Is

Ray tracing is a rendering method that simulates how light moves through a scene. Instead of drawing an image with quick approximations, it calculates the paths light rays take from the camera to surfaces and back, which produces reflections, shadows, and lighting that match how light behaves in the real world.

The technique has long been used in film and architectural work, where a single frame can take a long time to render. Gaming asks for the same kind of math to run in real time, which is why ray tracing has become a defining feature of modern graphics cards. NVIDIA describes ray tracing as simulating the physical behavior of light to bring real-life, cinematic-quality graphics. See what is a graphics card for where the work happens.

RT Cores: The Dedicated Ray Tracing Hardware

Real-time ray tracing performs the light simulation while the game is being played, every frame. The workload is heavy, so graphics processors add dedicated hardware called RT cores to accelerate the calculations. RT cores handle the repetitive ray intersection work, leaving the main shading units to process textures, materials, and the rest of the scene.

RT cores have evolved in generations. NVIDIA's comparison lists the RTX 20 series with 1st generation RT cores, the RTX 30 series with 2nd generation, the RTX 40 series with 3rd generation, and the RTX 50 series with 4th generation. The RTX 50 series uses the Blackwell architecture, and the 4th generation is built for Mega Geometry, a term for handling the large amounts of geometry in ray-traced scenes. GTX 10 and 16 series cards have no RT cores at all.

What Ray Tracing Changes Visually

The visible effect of ray tracing is most obvious in reflections and shadows. A polished surface shows the actual scene around it, a window casts light through glass with refraction, and a shadow falls correctly even when light is blocked by several objects. These are details that older rendering tricks can only approximate.

In a typical open-world scene, ray tracing makes window reflections and sun shadows behave correctly, which is why it is a headline feature for high-end gaming PCs. The most complete form is path tracing, which follows light through many bounces until it reaches the camera. NVIDIA describes the RTX 50 series as enabling path tracing with neural rendering for true-to-life graphics. More than 800 games and applications use RTX ray tracing and related features, according to NVIDIA.

• Reflections that mirror the full scene
• Shadows that behave with light sources
• Global illumination from light bouncing between surfaces
• Refraction through glass and water

The Cost of Ray Tracing and How It Is Managed

Ray tracing asks the graphics card to do much more work per frame than conventional rendering, so games typically apply it selectively. A scene may use ray-traced reflections or shadows while other effects are rendered in the traditional way.

Supporting technologies reduce the remaining load. DLSS Super Resolution reconstructs a high-resolution image from a lower-resolution input, and DLSS Ray Reconstruction replaces part of the light simulation with an AI-trained result. NVIDIA lists both as supported across RTX generations. See how DLSS and FSR upscaling works for the full picture.

For the same reason, a gaming PC chosen for ray tracing pairs a card with RT cores with enough graphics memory for the scene data and a display that matches the resolution you play at. The guide how to choose a gaming PC for ray tracing covers the details.

What to Look For in a Gaming PC for Ray Tracing

The deciding factor is the graphics card. A card with RT cores, meaning any RTX model from the 20 series onward, supports ray tracing. A GTX card does not, since it has no RT cores. NVIDIA also lists DirectX 12 Ultimate support for the RTX 20 through 50 series, which is the feature set that includes ray tracing on Windows.

Windows 11 itself requires a graphics card that is compatible with DirectX 12 with a WDDM 2.0 driver, so a current RTX card meets the platform baseline. Cards from the RTX 50 series, such as the RTX 5070, are worth comparing in the best RTX 5070 gaming PCs guide. When buying a prebuilt, read the spec sheet for the graphics card model before ordering; the article what to check before buying a prebuilt gaming PC explains how to read it. For a broader lineup, see the best prebuilt gaming PC guide.

What to pick for your play

Questions

Does every graphics card support ray tracing?

No. Ray tracing requires dedicated RT cores. NVIDIA's GTX 10 and 16 series cards do not include them, while RTX 20, 30, 40, and 50 series cards do.

What is an RT core?

An RT core is a dedicated unit inside a graphics processor that accelerates ray tracing math, such as testing where a ray hits a surface. It works alongside the card's regular shading processors.

Which generation of RT cores is newest?

The 4th generation, found in the GeForce RTX 50 series on the Blackwell architecture. The RTX 40 series has 3rd generation cores, the RTX 30 series has 2nd generation, and the RTX 20 series has 1st generation.

Is path tracing the same as ray tracing?

Path tracing is the more complete form of ray tracing. It follows full light paths through a scene with many bounces, producing the most realistic lighting. NVIDIA lists path tracing with neural rendering on RTX 50 series cards.

Does ray tracing work alongside DLSS?

Yes. DLSS Super Resolution and DLSS Ray Reconstruction are listed as supported across RTX generations. Ray Reconstruction specifically works on the light simulation to rebuild a high-quality ray-traced image.

How can I tell if a prebuilt gaming PC supports ray tracing?

Check the graphics card model in the spec sheet. If it is an RTX card with RT cores and DirectX 12 Ultimate support, it supports ray tracing. If it is a GTX card, it does not.