Go to : C:\Program Files (x86)\Steam\steamapps\common\No Man's Sky\Binaries\SETTINGS
     (Or basically, [any folder where you installed NMS]\Binaries\SETTINGS) [*]
Find the file "TKGRAPHICSSETTINGS.MXML" and open it with any text editor.
You will then search for the "GSync" option. It's "true" by default, change it to "false".