The Cheapest GPUs for Ray Tracing

Over the past seven years, Ray Tracing has entered the vocabulary of the modern day gamer in the weirdest way possible - NVIDIA chopped off their "GTX" branding for "RTX" in a bold move to show the world they were moving into a new era. And now games are being released that require it. And you need one on the cheap. How low can you go?

Ray Tracing is the term given to a method of rendering a video game where the light and light sources are physically simulated. Light rays bounce around in a 3D space, and interact with the objects that the rays "touch". The objects the light rays interact with have their own physical properties such as colour and texture, or transparency with materials like glass and water.

Ray tracing in a video game simulates light in reverse. Like ancient times when philosophers and mathematicians thought that humans shot beams of light out of the eye, rays are "constructed" from the perspective of the viewer.

From the viewer's "eye", a ray is cast on an object, and the game engine plots in real-time the path that this initial ray takes in a scene. It then calculates how light rays from a nearby light source would interact with objects and materials in your field of view. This is done for every pixel in the final image.

This is incredibly compute-intensive to do. There are ways to reduce the performance penalty by grouping pixels together that are close enough to the pixel that sends out the initial ray. But that's the "old" way to do ray tracing.

A more advanced method is now possible in real-time called Path Tracing. Instead of the game engine calculating the result of light interacting with things depending on what you're looking at (consequently tracking hundreds of initial rays at the same time), path tracing calculates the most likely path for light rays to bounce around in a scene.

Instead of tracking light rays for every pixel, path tracing also lowers the number of light rays tracked in a scene, and only does the lighting calculations for objects that the light is likely to interact with. Adding more light sources makes path tracing more taxing to run, but the overall effect is better.

In prior generations of video games, light sources in a video game were "baked in" because the ray tracing for realistic lighting and shadows was done in the studio by developers. The results were saved as snapshots called a Lightmap. Shadowmaps would also be created where objects that needed to have shadows would have a texture added to simulate one.

With ray tracing and path tracing now possible on the fly, creating lightmaps is no longer something developers need to do, and the shadows work just like real shadows. They are realistic, sharp, and well-defined.

To do ray tracing in real time without bogging down the GPU, you need ray tracing cores. These are dedicated hardware units that only do the math required to simulate light rays in an environment. The more RT cores you have, the more light rays you can simulate and the faster you can complete the work.

"Bigger number better", as they say in the industry. But how much money do you need to spend to get passable-to-decent RT performance? It's cheaper than you think.

MSI Radeon RX 6400 AERO ITX

The cheapest AMD Radeon GPU with some ray tracing capability is the Radeon RX 6400, seen above in a design by MSI. AMD's partners made dual and single-slot RX 6400 cards for a single purpose - slapping them into workstations as a cheap way to accelerate apps like Blender and Photoshop.

It's not the best performing card by any stretch of the imagination when it comes to running a game with RTX, but the twelve Ray Accelerator units can actually run Cyberpunk 2077 with some ray tracing.

NVIDIA's competing card was the GeForce GTX 1650, which was a weird branding decision. The GTX 1650 lacked NVIDIA's premier branding for the feature but nonetheless included RT cores, primarily because the Turing-based TU116 GPU was used in some of NVIDIA's Quadro and T-series GPUs for workstations. Like the RX 6400, it can't run most games with decent performance when using Ray Tracing, but you know... the option is there.

ASRock Arc B580 Challenger OC

The real entry-range options for gamers today include the AMD Radeon RX 7600, the Intel Arc B570 and B580, and the NVIDIA GeForce RTX 3060 and RTX 4060 8GB. And perhaps the Radeon RX 7600 XT, if the budget stretches that far.

For most of these cards, ray tracing compatibility is a tick-box feature, but there are some real improvements found on Intel's B570 and B580, which also offer the most amount of VRAM for the budget market - 10GB and 12GB of GDDR6 respectively. In fact, the Arc B580 might well be the de facto choice for gamers at the R6500 price point assuming the RX 7600 XT isn't on sale - the Intel card is plenty fast enough for 1440P displays for most games, and is capable of running Cyberpunk 2077 with full path tracing (not well, but capable of it).

But Cyberpunk 2077 is only one part of the story. Indiana Jones and the Great Circle can't run at acceptable frame rates on most GPUs because ray traced lighting is a requirement for the game. That the Arc B580 can run the game at 1080P with medium settings, and runs close to an average of 60fps, bodes well for the card's ability to run other modern games with RT requirements in the future. NVIDIA's RTX 4060 8GB is the closest competitor to the B580 in terms of ray tracing performance.

XFX Radeon RX 9070 SWIFT OC

True RT performance doesn't really enter into the picture until you double the budget and shoot for either the AMD Radeon RX 9070 or the NVIDIA GeForce RTX 5070. Both retail for around R14,500 in the current market.

Across a range of reviews from third parties, looking at non-RT benchmark results, the RX 9070 is almost twice as fast as the GeForce RTX 4060 Ti 16GB for a similar cost in Techspot's review. It outpaces the Radeon RX 7800 XT and RX 7900 GRE too, as well as the venerable RTX 3090, and on average pulls slightly ahead of the RTX 5070.

At launch, the RX 9070 also does well in benchmarks for ray-traced games, pulling mostly in line with the GeForce RTX 4070 and the Radeon RX 7900 XTX - AMD's flagship from two years ago. There are some indicators that improvements are still needed, like Techspot's results for Black Myth: Wukong and Alan Wake II. Benchmarks for both games at different resolutions show that there may be room for driver improvements in the near future.

That's where NVIDIA's strengths lie with the RTX 5070 this generation. Ray Tracing performance is excellent across the board and upscaling using DLSS4 is the best it's ever been. The RTX 5070 is now the default choice for mid-range buyers who have a preference for Team Green, even if it has less VRAM than the RX 9070.

Both of these cards are the new normal for the mid-range market, the minimum you need to budget for to have enough performance to enable all the bells and whistles in your favourite games, as well as future titles we have yet to see. Either one is a solid choice.

Just uh... make sure to use a tape measure to see if they fit into your current chassis. These cards are getting big.