Very slow render, and not using much CPU or GPU

I am rendering a video that I transformed and cropped. It's only using about 5% CPU and 5% GPU, and it's going very slowly. 3 hours to render a 45 minute video. Any idea why it's going so slow? All the CPU, GPU, disk, and network metrics are basically idle.

Original is mp4 h264 1344x748 framerate 37, AAC stereo 48khz
Destination is mp4 h264 720x480 framerate 24, AAC 192kb/s

If you're monitoring activity with Windows task manager, you must manually select to monitor Compute graph for the GPU specifically.

And if it's the free version on a PC, you might be driving without full power.

What if it's also a low performance laptop or...?

@Dissolve25, what's your PC configuration?

What if it's also a low performance laptop or...?

@Dissolve25, what's your PC configuration?

Updated my signature to include system specs.

Hmm, do you have a dedicated GPU?

Hmm, do you have a dedicated GPU?

Ack! How did I leave that off the sig. Yes, updated sig. NVidia GeForce GTX 1660.

But @Uli Plank said free version of Resolve doesn't run at full power. I'm looking at differences of free vs Studio, and I see neural engine, various tools. I don't see a reason to believe the free version will run slow.

I figured it out. I went to Davinci Resolve > Preferences > System > Memory and GPU, and I set GPU Processing Mode: CUDA

Restart Davinci Resolve, and it says "No CUDA GPU available," so then I updated my nvidia drivers, rebooted, and it's fixed. Now I'm getting 90% cpu usage, 50% GPU usage, and the whole video renders in 3 minutes.

Hmm, do you have a dedicated GPU?

Ack! How did I leave that off the sig. Yes, updated sig. NVidia GeForce GTX 1660.

But @Uli Plank said free version of Resolve doesn't run at full power. I'm looking at differences of free vs Studio, and I see neural engine, various tools. I don't see a reason to believe the free version will run slow.

Uli probably referred to the fact that the free version will not use GPU to decode and encode video. But GPU effects should be equal in performance between the two.

Interesting how you were able to run Resolve at all without proper GPU detection, and you didn't run off an integrated GPU because you have none.

That happened to me as well when my driver was too old.
It couldn't use CUDA because the version that DVR wanted wasn't supported, but it was able to fallback top OpenCL.

Interesting. OpenCL may not be as optimized as CUDA but 3hrs vs 3 mins due only to OCL. There must be more to it.