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Re: Very low gpu usage (rx 580)

PostPosted: Mon Feb 18, 2019 12:30 am
by pm5k00
I know this post is old, but after searching for this same question but with no answers, I though I'd post what I found out.

Initially I thought My XFX RX 580 8GB GTS edition was not being utilized as Windows Task Manager was reporting 1-4% usage. After browsing this forum and reddit to no avail, I decided to do some further investigating. I opened my case and saw the fans on the GPU spinning, which is odd as the fans should be off if the GPU is under 50*C. So i fired up GPU-Z and it reported 100% usage and a temp of 64*C.

So for whatever reason windows task manager is not reporting the utilization properly (it does however still report the amount of GPU memory being used accurately) .

TLDR: Windows Task Manager < GPU-Z .

Re: Very low gpu usage (rx 580)

PostPosted: Mon Feb 18, 2019 10:08 pm
by bruce
The key information is that Windows is an Operating System that manages tasks on your CPUs, not your GPUs. Task Manager does not report the status of the GPU, it reports the utilization of the CPUs. GPUs are essentially unmanaged -- they're treated as an external coprocessor by the OS.

As you discovered, GPU-Z can poll the GPU and report what's happening there.

The FAHCore_2* is a CPU task which prepares work packets for the GPU and transmits them across the PCIe bus and then waits to receive the results. (Of course your screen may be the target of some processing, too when the output happens to be video.

Re: Very low gpu usage (rx 580)

PostPosted: Mon Feb 18, 2019 11:30 pm
by toTOW
On Windows Task Manager, you have to select what to display for the GPU to be able to monitor load from FAH. On NV GPUs, "3D" will show nothing interesting, the load is on "CUDA" with latest drivers ... sometimes, it might also show on "Compute_0" or "Compute_1" depending on the GPU and drivers used ... I don't know how it will be with an AMD GPU ...

Re: Very low gpu usage (rx 580)

PostPosted: Tue Feb 19, 2019 12:23 am
by Theodore
I would affirm what toTOW has to say.
Though, unless you've installed the CUDA drivers from NVidia, there won't be any CUDA window in task manager, and you'll find it in any of the compute_0 (or compute_1) selections under GPU.