I have a CHG90 also - from what I can tell, The monitor has three options for freesync support "Off", the "Standard Engine", and the "Ultimate Engine" (I do not know the difference between standard and ultimate).
To see if your Freesync support is turned 'on' in the monitor press the power button once to bring up the menu, then toggle the power button away from you (toward the back of the monitor) to select the 'menu'. Push the power button again to open the display menu for the monitor.
You should now see the menu on the right side of the display just above the power button. There should be 5 circles across the top with various things in them. The 4th one ro the right is the status of FreeSync on your display. If it says 'On', then it is on already.
However, I have turned these things on, switched between 'standard' and 'ultimate' without success.
I also tried restarting my PC and monitor, reinstalling the drivers for the card and the monitor, and swapping to another display port on my gtx1080, but NVIDIA will not detect that the monitor has FreeSync (even though it is obviously ON and should be working).
I am going to buy the Radeon Vega VII on release next month, so this should only be a problem for me for another 20 or so days till the new AMD video card arrives which should fully support FreeSync properly.
I wish you luck with the problem though, if you happen to find a solution, please post it here so I can turn it on for the next 20 days or so
thanks!
(As a side note, anyone interested in a lightly used EVGA GTX 1080 SC?
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