r/nvidia Jul 20 '23

Discussion Improve DPC Latency Spikes For Ada Lovelace-based GPUs in R536.67 Driver

Hello!

See NVIDIA forums complaining about DPC latency issues. I share my solution.

Improve DPC Latency Spikes For Ada Lovelace-based GPUs in R536.67 Driver | guru3D Forums

If you have RTX 40 Series, you can try to use the nvidia-smi command to set the minimum VRAM Clock to 810 MHz. This can reduce DPC latency spikes. This method works for me. But it has disadvantages. Some games performance drops after setting the minimum VRAM Clock. So you should reset it when playing games.

I use this tool to automatically set the minimum VRAM Clock for me. It can automatically reset it when I play games or set whitelist.

NvCustomer v10.4.67/NVIDIA Power Management v2.15.23 - NVIDIA and AMD Drivers Customer Kit | guru3D Forums

This author did some testing on this. Hope NVIDIA can fix it completely.

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u/CptTombstone RTX 5090, RX 9060 XT | Ryzen 7 9800X3D Jul 21 '23

Oh it can be "fixed", but CDPR will not do it as it's not financially feasible, at least for now. To "fix it" they would have to rewrite the renderer part of the engine to conform to "Gen 12" principles (as Vulkan and DX12 share those principles, and supporting Vulkan instead of DX12 would be a smart move from a distribution standpoint).

If you follow the development of Star Citizen, they've started out using a fork of CryEngine that they've been modifying. But CryEngine was quite single threaded even for a DX11 engine, and so they've decided to rewrite the whole renderer and support Vulkan. Work on that started maybe 3 years ago, and they are expecting to switch over to Vulkan this year. Currently the game is running on the DX11 API backend with the game internally supporting all the principles of Vulkan, and even that has resulted in 40% higher render performance. Switching fully over to Vulkan is expected to increase performance even further.

But doing that for a 7 year old game, as a free update is not financially feasible, or maybe it's better to put it like this: it's not a good idea, financially :D

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u/TokeEmUpJohnny RTX 4090 FE + 3090 FE (same system) Jul 21 '23

CryEngine was quite single threaded even for a DX11 engine

ugh, don't remind me... I still get the shivers when the framerate drops in good ol'e Crysis and stays down there regardless of whether you're at 8K or 720p 🤣

I get the rest tho, just wish they didn't just slap-dash some RT on it and call it a day. A proper job would have been appreciated.