Random stutter, with or without Ubershaders

[daninthemix]

I'm playing Super Mario Galaxy, internal resolution is 4K.

Everything is completely smooth except every few minutes, I get a stutter (that lasts for a second or so). I've had Windows Task Manager up and these stutters don't appear to correlate to either CPU or GPU usage, which stay constant at around 20% (CPU) and 85-100% (GPU).

I get this issue, at around that interval, regardless of the Ubershader setting.

So I'm just wondering:

1) Should my GPU usage be that high? (a GTX 1080)
2) What can this stutter be, considering it seems to not be shader related.

[ExtremeDude2]

What are your graphics setting?

[JonnyH]

The NVidia drivers have a bug that means that ubershaders on both OpenGL and Vulkan backends still stutters.

Does the stutter still happen if using the DX11 backend?

[daninthemix]

I'm using the D3D11 backend.

Some more info: just tried the Ishiiruka fork and that has much more reasonable GPU usage (25% or so, at 4K internal res), and crazily CPU usage has dropped to around 4%. I've still seen one or two stutters though, in a ten minute play session.

Am wondering whether this is something like the CPU downclocking itself.

[KHg8m3r]

In the Nvidia Control Panel, go to 3D settings, make a profile for Dolphin, and make sure it is using maximum performance.
Also go to Windows Power Management and make sure you have Fast Start disabled and that you're using a High Performance

[daninthemix]

I always have Nvidia on prefer max performance. Just tested with the power plan on high performance and it made no difference.

[daninthemix]

Fixed: Dolphin doesn't like G-sync. Disabling G-sync for dolphin.exe has fixed this.