nvidia-settings -a GPUFanControlState=1 -a GPUTargetFanSpeed=70
nvidia-settings -a "GPUFanControlState=1" -a "GPUTargetFanSpeed=70"
I don't think it works without the quotes, but not 100% certain.
Well, my rig is coming Tomorrow, so I will be able to report if this command blast all the gpu fans to the indicated value or not.
Unfortunately i googled a little and it seems that this setting is not persistent between reboots