Blackmagic Forum

Hello,
I'm doing some tests using an RTX 5090 card, rendering 4K HDR videos using the nVidia NVENC encoder (DaVinci Resolve 20).

Source videos have the following specs:

Code: Select all

Format: HEVC
Format profile: Main 10@L5.1@High
Codec ID: hvc1
Bit rate: 84.6 Mb/s
Width: 3 840 pixels
Height: 2 160 pixels
Display aspect ratio: 16:9
Frame rate mode: Variable
Frame rate: 60.000 FPS
Color space: YUV
Chroma subsampling: 4:2:0
Bit depth: 10 bits
Color range: Limited
Color primaries: BT.2020
Transfer characteristics: PQ
Matrix coefficients: BT.2020 non-constant
Codec configuration box: hvcC


for encoding, I use the following nvenc settings:

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Quality: Restrict to 90000Kb/s
Encoding Profile: Main10
Keyframes: Automatic
Frame Reordering: Yes
Rate Control: Variable Bitrate
Split Mode: Split
Preset: Very Slow
Tuning: Ultra High Quality
Two Pass: Full
Lookahead: 16 frames
Disable Adaptive B-Frame
AQ Strenght: 8


The encoding process runs rendering almost 30/35 frames per second.
I've noticed the 3 encoders are barely used, though: they're never over 40/45% loaded.



Any reason / explanation? When I was using an RTX 4090 and DaVinci Resolve 19 I remember they were always used over 80% with the same settings.

I'm having the same issue. The 3 video encoders were all sitting around 21% during the entire time the render was going and the GPU utilization never passed 40% and was only pulling 190w.

I would like a solution to this as well because feels like I'm leaving a lot of performance on the table.

My render settings were: Format:

MP4 Codec: AV1 Type: Nvidia

3840x2160 60FPS

Quality restrict to 80,000 kb/s

Profile: Main
Key Frames: Auto

Frame reordering checked

Rate control QP
Split Mode: Split
Preset: Medium
Tuning: High Quality
Two Pass: Disable

Constant QP, 87, 112, 134

Lookahead 16 frames

Enable Adaptive b-frames checked

AQ Strength 8



PC specs:

GPU: RTX 5090 Gigabyte Aorus Xtreme Waterforce AIO
CPU: Intel Ultra 9 285k
Ram: 48GB (2x24) 8000MT/S CL40 CUDIMM
Motherboard: Asus z890 Apex

Misty_Kathrine wrote:I'm having the same issue. The 3 video encoders were all sitting around 21% during the entire time the render was going and the GPU utilization never passed 40% and was only pulling 190w.

I would like a solution to this as well because feels like I'm leaving a lot of performance on the table.

My render settings were: Format:

MP4 Codec: AV1 Type: Nvidia

3840x2160 60FPS

Quality restrict to 80,000 kb/s

Profile: Main
Key Frames: Auto

Frame reordering checked

Rate control QP
Split Mode: Split
Preset: Medium
Tuning: High Quality
Two Pass: Disable

Constant QP, 87, 112, 134

Lookahead 16 frames

Enable Adaptive b-frames checked

AQ Strength 8



PC specs:

GPU: RTX 5090 Gigabyte Aorus Xtreme Waterforce AIO
CPU: Intel Ultra 9 285k
Ram: 48GB (2x24) 8000MT/S CL40 CUDIMM
Motherboard: Asus z890 Apex

I've done some additional tests, and for me, the issue is caused by the tuning parameter set to the new value, 'Ultra High Quality.'
If I lower it to an inferior setting, the encoders consistently operate at 85–90%.
It seems like this new tuning parameter has some issues. I understand that 'Ultra High Quality' is supposed to be slower, but not to the point of barely utilizing the hardware.

I've also tested the parameters you mentioned, and guess what? I can replicate your issue—low GPU utilization even with the 'Medium' preset. However, if I change the preset to 'Very Slow,' performance actually improves (70–75% GPU utilization).

These settings are a mess, if you ask me. There's something wrong with how the 'Tuning' and 'Preset' parameters interact with each other. Tweaking them leads to inconsistent results. Not exactly ideal when you own a €3,200 GPU, only to see it running at 40%.

By the way, I'm using NVIDIA drivers version 576.52.

I've also tested the parameters you mentioned, and guess what? I can replicate your issue—low GPU utilization even with the 'Medium' preset. However, if I change the preset to 'Very Slow,' performance actually improves (70–75% GPU utilization).

These settings are a mess, if you ask me. There's something wrong with how the 'Tuning' and 'Preset' parameters interact with each other. Tweaking them leads to inconsistent results. Not exactly ideal when you own a €3,200 GPU, only to see it running at 40%.

By the way, I'm using NVIDIA drivers version 576.52.

Very slow huh? I'll have to try that, thanks for the tip. It definitely seems like a mess, I don't know if it's a resolve issue, or just a driver issue. I'm also using 576.52 of the Studio Driver and the latest bios for my motherboard, so I have everything up to date.

Anyway, I try my rendering my next video in very slow and see how that goes and hopefully the next resolve update or NVIDIA driver improves things.