Low FPS in Unreal engine, but GPU usage is low as well

Question

I am running an Unreal Engine 4 project which has many high quality assets. My computer is fairly strong:

• CPU: AMD Ryzen 5 3600 6-Core
• GPU: GeForce RTX 3060 SSD: Lexar 500GB NM610 M.2 NVMe SSD
• RAM: 2 HyperX Fury DDR4 8 GB RAM = 16 GB RAM in total
• Motherboard: Gigabyte Technology, A520M DS3H AC
• OS: Windows 10 Home

At certain points my fps drops down to 30, sometimes a bit lower. In windows task manager under the 'performance' tab, I see that my graphics cards only has about 5% usage. However, when I run the 'nvidia-smi' command in command prompt, under 'volatile GPU-utilization' I get 100% usage. What is the actual usage of my graphics card? Should I disregard what windows task manager is saying?...

Answer 1

Unreal has built in profiling tools to help you identify where the bottleneck is. Open the console and type stat unit and it will show you times in milliseconds for the CPU (both the game thread and the draw thread) and the GPU. See https://docs.unrealengine.com/4.27/en-US/TestingAndOptimization/PerformanceAndProfiling/StatCommands/#unit for details and a list of all the stat commands.

Also note that Unreal will limit the frame rate to about 62 FPS by default, which isn't always helpful when testing performance. You can use the console command t.maxfps 500 to change that limit to 500 FPS. You can also change it permanently in the project settings.

Answer 2

stumbled upon this forum thread: https://linustechtips.com/topic/1034616-task-manager-not-reporting-correct-gpu-usage/ I think windows task manager is outputting the incorrect usage. I remember owning a laptop from years ago that always said my RAM usage was maxed out. I think windows task manager is not built well!