GPU load data... who do I believe?

IsaacNewton

In the process of testing my Nvidia cards, I downloaded TechPowerUP GPU-Z, to monitor GPU activity. The confusing thing is this, the TechPowerUp monitor tells me that my GPUs are working at max but Windows Task manager says they are doing nothing! Who is right?

See the attached image; note that:

1) DAZ Studio says that the CPU and both GPUs are being used.

2) TechPowerUp says that the GPUs are running at  around 98% GPU load (only one is shown at a time, but the story is the same for both)

3) Task manager shows GPU Utilisation between 0% and 1%)

Am I misunderstanding Task Manager? Is it lying? Is TechPowerUp lying? I'm confused.

Richard Haseltine

Rendering is, I suspect, "none of the above" as far as Windows Task Manager goes - it doesn't give a raw usage value.

kenshaw011267

Task manager is not very good at monitoring GPU's. GPU-Z is pretty much the standard for monitoring GPU's. I'd trust GPU-Z.

NorthOf45

In Task Manager, you need to change one of the views to Compute_0 (click on a graph heading, say, Copy, or VideoEncode). Also, in Details view, you can add several colums for GPU info.

ebergerly

NorthOf45 said:

In Task Manager, you need to change one of the views to Compute_0 (click on a graph heading, say, Copy, or VideoEncode). Also, in Details view, you can add several colums for GPU info.

Yes, in fact Windows Task Manager is the best source for info on what the GPU is doing since it does the scheduling and managing via "VidMm" and "VidSch". For some reason folks don't want to believe that, but it's true.

And yes, you need to select the correct engine first to be displayed, since Task Manager defaults to showing GPU charts for engines that gamers, not Iray, tend to use. And typically, for whatever reason, Iray tends to use the "compute_0" engine, not what folks seem to intuitively presume ("3D"). 

Here's a link to a blog from the Microsoft Lead Engineer for the VidMm and VidSch that explains in detail how Task Manager is the authority and why, in case anyone wants the facts:

https://devblogs.microsoft.com/directx/gpus-in-the-task-manager/

Note his comment on W10's authority in the GPU data department:

"Further, because VidMm and VidSch are the actual agents making decisions about using GPU resources, the data in the Task Manager will be more accurate than many other utilities, which often do their best to make intelligent guesses since they do not have access to the actual data."

Oh, and here's a thread I created last year with a tutorial on how to properly use the Task Manager for GPU data:

https://direct.daz3d.com/forums/discussion/280521/ot-psa-windows-10-performance-monitoring#latest