They guys over at TechPowerUp have discovered some interesting limitations on when and how you can enable DLSS in games that support it. If you don’t know DLSS is NVIDIA’s alternative to traditional anti-aliasing. In our testing with the GTX 2060 and GTX 2080 when DLSS was enabled performance increased quite a bit. You would think that if your game supports DLSS, you can just turn it on, but that does not seem to be the case.
In their testing with Metro Exodus it appears that with an RTX 2060 you can’t even use DLSS at 4K. Even more interesting RTX 2080 and RTX 2080 Ti users can’t use DLSS and RTX together at the most popular resolution right now, 1920 x 1080!
In Battlefield V they noticed a similar trend, albeit a bit different. Using the flagship RTX 2080 Ti you cannot use RTX and DLSS even at 1440p.
I always wondered why in our testing with DLSS in the Final Fantasy XV benchmark you could only run it at 4K.
TechPowerUp did in fact contact NVIDIA about this and they said that DLSS is most effective when the GPU is at maximum work load, such that if a GPU is not being challenged enough, DLSS is not going to be made available. Accordingly, this implementation encourages users to turn on RTX first, thus increasing the GPU load, to then enable DLSS. I guess this would be the reason why the RTX 2080 and RTX 2080 Ti do not get DLSS at lower resolutions.
This still does not make a whole lot of sense, I mean if you turn off Vsync your GPU load will be around 100%. All of the cards in the RTX family have a different number of tensor cores (which handle DLSS). DLSS works on a frame-by-frame basis and these cores determine how many frames can be processes at one time. So the tensor cores could become a bottleneck when gaming if restrictions were not put in place. This does explain why higher-end cards can’t use DLSS at lower resolutions.
So as of right now it appears that there are restrictions on DLSS depending on what RTX card you have and the specific game. We only wish this was made more apparent to the end-user.