Nvidia frame generation artificially caps raw FPS

User Support Hub Hardware & Peripherals
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I discovered this by accident, doing another test. I just placed myself in the middle of the ocean at a small airfiled in Seychelles. I used the ultralight to get also the lowest FPS hit. Monitor runs at 120Hz, G-sync enabled for fullscreen and V-sync enabled at Nvidia panel, as without it I was unable to make G-sync work in Windows 11.

Without frame generation enabled I hit 80 FPS with a main thread latency around 10ms, so perfect. An OSD FPS counter in my monitor displays those 80 FPS too, so that´s consistent. G-sync also works.

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After enabling frame generation in game the FPS counter in game decreases to 60 FPS, and the main thread latency increases to around 16 ms, matching those 60 FPS therefore. The OSD FPS counter in my monitor displays 116 FPS so frame generation indeed works and it´s doubling the raw FPS output from game. I already tested that feature and works well in other scenarios too. G-sync also works in this case.

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But why is game showing its raw FPS reduced to 60 FPS when it was previously 80 FPS? I understand output should be 160 FPS (limited to 120 FPS as my monitor can´t work at 160 Hz), but keeping anyway the raw one at 80 FPS as before.

It appears as if frame generation is applying the typical 60 FPS cap intended when V-sync is applied in game, but game settings still show V-sync is indeed disabled both in menu and in the UserCfg.opt file. However what gets activated in game options after enabling frame generation is Nvidia reflex low latency mode, and you can´t disable it as the option is greyed out.

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Cheers

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The ingame FPS counter, does not include FG. It cannot count the extra generated frames for a technical reason I guess, because these extra frames are generated by the gpu without any game engine inputs. So your actuall output FPS was 120 and not 60.

If you use an external tool for FPS counting, it will show the 120 fps.

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Thanks. I started to use FG just couple of weeks ago, so I need to get used to it.

I changed monitor refresh to 144Hz (max allowed by my monitor) and ingame FPS counter goes to 67 FPS with external showing 134 FPS, so there´s no 60 FPS cap there but a 72 FPS one, as I was not able to pass 72 FPS even if I reduced settings. It´s still a bit strange as it seems render is done at 1/2 refresh rate to double it afterwards by including the new frames. That would explain the 60 FPS cap in case of a 120 Hz refresh.

Cheers