If you have a DisplayPort 1.4 then use that one, if not probably best to buy it because it won't work with HDMI.
You can check the Wiki pages for HDMI and DisplayPort there you can see the differences.
Nvidia Control Panel > Change Resolution. Once in that screen there should be the option to change it to 144hz, make sure your using a connection that supports it (DVI/DisplayPort).
If you have a DisplayPort 1.4 then use that one, if not probably best to buy it because it won't work with HDMI.
You can check the Wiki pages for HDMI and DisplayPort there you can see the differences.
Nvidia Control Panel > Change Resolution. Once in that screen there should be the option to change it to 144hz, make sure your using a connection that supports it (DVI/DisplayPort).