DLSS Frame Generation on RTX 20/30 series GPUs? Portal Prelude RTX bug causes confusion

No, DLSS does not work on RTX 20/30 series GPUs in Portal Prelude RTX – Nvidia Confirms

Earlier this year, Portal Prelude, a popular prequel mod for Valve’s Portal, received a full-on RTX remaster with full ray tracing and DLSS support. Now, gamers have uncovered that they can enable Nvidia’s DLSS Frame Generation technology within the mod using RTX 20 series and RTX 30 series graphics cards. This is something that shouldn’t be possible.

This has sparked rumours that Nvidia’s older RTX GPUs are capable of DLSS Frame Generation. These rumours claim that Nvidia are blocking this functionality from older RTX GPU users to boost RTX 40 series sales. If DLSS Frame Generation works on older RTX GPUs in Portal Prelude RTX, Nvidia are in a lot of hot water. The problem with these rumours is this. DLSS Frame Generation doesn’t work on older RTX GPUs, even if it can be enabled.

While enabling frame generation on RTX 20/30 series GPUs is possible, this is due to a bug. Yes, framerate gains can be seen, but not because frame generation is working. This bug causes duplicate frames, not frame generation. Rendered frames are simply displayed twice when DLSS Frame Generation is used with unsupported hardware. This is what allows FPS counters to display higher framerates. So no, DLSS Frame Generation is not working on RTX 20/30 series GPUs.

Below is what Nvidia had to say on the matter on their GeForce forums. Below, we can see Nvidia’s confirmation that this DLSS oddity is a bug. DLSS Frame Generation does not work on pre-RTX 40 series GPUs.

Why does it seem like DLSS Frame Generation works on RTX 20 and 30 series GPUs in Portal Prelude RTX?

A: We’ve noticed that some members of the PC gaming community, like Discord Communities before it, have encountered a bug in an old v1.0.1.0 DLSS DLL that falsely appears to generate frames on 20/30-series hardware. There is no DLSS Frame Generation occurring—just raw duplication of existing frames. Frame counters show a higher FPS, but there is no improvement in smoothness or experience. This can be verified by evaluating the duplicated frames using tools like NVIDIA ICAT, or viewing the error message in the Remix logs indicating an error with frame generation.

DLSS frame generation DLLs have since fixed this bug, and NVIDIA will be issuing an update to RTX Remix in the future to prevent further confusion when frame generation is behaving incorrectly.

Why DLSS 3 Frame Generation does not work on older RTX hardware

Nvidia’s DLSS Frame Generation technology requires the advanced optical flow capabilities of Nvidia’s RTX 40 series GPUs. This is why DLSS Frame Generation does not work on older RTX 20 series and RTX 40 series graphics cards. Nvidia designed their frame generation technology around the specific hardware capabilities of their latest GPUs. Without the optical flow acceleration of Nvidia’s RTX 40 series GPUs, DLSS Frame Generation simply doesn’t work.

An old, buggy, dll file is the cause of Portal Prelude RTX’s DLSS frame generation bug. Newer versions of RTX remix include a fixed version of this file. Portal Prelude RTX and Portal with RTX are only possible thanks to Nvidia’s RTX Remix technology.

You can join the discussion on Portal Prelude RTX’s Frame Generation not working with RTX 20/30 series GPUs on the OC3D Forums.

Mark Campbell

Mark Campbell

A Northern Irish father, husband, and techie that works to turn tea and coffee into articles when he isn’t painting his extensive minis collection or using things to make other things.

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