nvidia Is my GPU's default fan curve really supposed to be hard-capped at 50%?

apetresc · February 25, 2019

I have an NVidia GTX 1080Ti (this SKU specifically, if it makes a difference) which I have not (yet) messed with in any way, in terms of changing any of its default settings. I use it exclusively for ML training which can basically make it thermal throttle at its default limit of 84°C instantly.

However, the strange thing I've noticed is that even when it's thermal-throttling at 84°, the fan speed never goes up above 50%. This is confirmed by any measurement I've been able to make (nvidia-smi, GPU-Z, the monitoring tool that came with my motherboard, etc), and it's true both on Linux and Windows. The fan speed grows gradually up to 50% and then never budges even 1% higher than that, even after hours of sustained 84°C utilization.

I know I can adjust the fan curve using overclocking tools like tuxclocker, and that's what I intend to do, but first I wanted to find out why the default is so low in the first place. Do I just have a misconfigured card, or is there some good physical reason why it would be impossible to go above 50% without manually overriding the fan curve? Is the manufacturer worried about damage to the fans if they ran at high speed for a long time? Is there some sort of steep diminishing returns on cooling above a certain RPM that would make it useless to run them any faster than that? What gives?

Thanks!

monjessenstein · February 25, 2019

The thing with fans is that as you increase them in speed, the less and less useful they become in cooling something. Blower style cards, since they only have one fan, need to pretty much do the work of two fans, meaning they have to spin exceptionally faster than normal ones to reach the same effect in cooling. There's no problem with running fans faster, but you start to make A LOT more noise then what you're gaining in terms of temperature. Nvidia probably limited the fan just to protect your ears.

PS. look at the graph in the video, as you can see the amount of heat effectively carried away dimishes drasticly with increasi in air velocity a.k.a. air speed, or in the case of fans rpm speed.

Origami Cactus · February 25, 2019

My 1080ti goes to 100% easily, idk why your model has capped the fan speed to 50%.

Maybe try MSI afterburner and manually set the fan speed to 98%(i dont like 100%), and see what happens.

But blower fan at 100% will be very very loud.

Jurrunio · February 25, 2019

that's odd, founders edition 1080ti regularly do 70% fan speed under sustained max load at stock. Misconfigured fan profile if you ask me, you can reflash the BIOS if you bother to do so.