The S23A750D only outputs 120hz via Displayport. Hope you own AMD.
I got this monitor and using the DP cable with a DP -> miniDP adapter because my 6950s dont got regular DP, does this affect the refresh rate?
It says 120hz in my options, but it doesn't really seem like it. also it only selects 120hz Vertical sync turned ON, in fullscreen, no windowed mode. If I use windowed mode VS on, it caps out at 60 fps, but when I choose fullscreen, it caps at 120hz.