That's odd, since you can use ray tracing without DLSS. I'm very sure it uses denoising even then.
There may be some confusion between upscaling and denoising. You might notice I keep editing my comment because it’s really really hard to find old Nvidia release announcements.
Update: https://youtu.be/6O2B9BZiZjQ looks good around 3:54
It adds frames since I think 3.0.