The new part is frame generation. DLSS 3 will generate an entirely unique frame every other frame, essentially generating seven out of every eight pixels you see. You can see an illustration of that in the flow chart below. In the case of 4K, your GPU only renders the pixels for 1080p and uses that information for not only the current frame but also the next frame.
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Frame generation isn’t just some AI secret sauce, though. In
DLSS 2 and tools like FSR, motion vectors are a key input for the upscaling. They describe where objects are moving from one frame to the next, but motion vectors only apply to geometry in a scene. Elements that don’t have 3D geometry, like shadows, reflections, and particles, have traditionally been masked out of the upscaling process to avoid visual artifacts.
Masking isn’t an option when an AI is generating an entirely unique frame, which is where the Optical Flow Accelerator in RTX 40-series GPUs comes into play. It’s like a motion vector, except the graphics card is tracking the movement of individual pixels from one frame to the next. This optical flow field, along with motion vectors, depth, and color, contribute to the AI-generated frame.
It sounds like all upsides, but there’s a big problem with frames generated by the AI: they increase latency. The frame generated by the AI never passes through your PC — it’s a “fake” frame, so you won’t see it on traditional fps readouts in games or tools like FRAPS. So, latency doesn’t go down despite having so many extra frames, and due to the computational overhead of optical flow, the latency actually goes up. Because of that, DLSS 3 requires
Nvidia Reflex to offset the higher latency.
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DLSS is executing at runtime. It’s possible to develop an algorithm, free of machine learning, to estimate how each pixel moves from one frame to the next, but it’s computationally expensive, which runs counter to the whole point of supersampling in the first place. With an AI model that doesn’t require a lot of horsepower and enough training data — and rest assured, Nvidia has plenty of training data to work with — you can achieve optical flow that is high quality and can execute at runtime.
That leads to an improvement in frame rate even in games that are CPU limited. Supersampling only applies to your resolution, which is almost exclusively dependent on your GPU. With a new frame that bypasses CPU processing, DLSS 3 can double frame rates in games even if you have a complete
CPU bottleneck. That’s impressive and currently only possible with AI.