coolbits nvidia-settings Error parsing assignment Missing attribute name

I am trying to overclock a Nvidia graphics card.

Ubuntu 16.04.2 LTS + NVIDIA Driver Version: 384.47

After editing /etc/X11/xorg.conf

Section "Device"
Identifier     "Device0"
Driver         "nvidia"
VendorName     "NVIDIA Corporation"
BusID          "PCI:1:0:0"
Option         "Coolbits" "28"
Option         "AllowEmptyInitialConfiguration"
EndSection

(PCI Bus matches up with the device)

Rebooting, and then trying to adjust settings using nvidia-settings, I get:

ERROR: Error parsing assignment '[gpu0]GPUPowerMizerMode=1' (Missing attribute name).
ERROR: Error parsing assignment '[gpu0]GPUMemoryTransferRateOffset[3]=1600' (Missing attribute name).
ERROR: Error parsing assignment '[gpu0]GPUGraphicsClockOffset[3]=100' (Missing attribute name).

The additional overclocking options are not available in the GUI of nvidia-settings either.

I have tried different drivers versions, reinstalled Ubuntu about 6 times using various GUI's and package options.

I managed to get this right on 1 previous machine, but I can't for the life of me remember what I did.

I suspect that Coolbits is not being activated, but don't know how to confirm this.