Stuck at 60hz on Preadator x34. Using display port, can't go above 60 in Nvidia control panel either

sp2004

Hi, on my desktop I am running a GT 720(which is really old) and using an active HDMI to display port adapter (the adapter supports 120hz at 1080p) but for some reason even with the overclock to 100hz I can't seem to get 100hz @1080p. On my Samsung TV I am able to get 120hz @1080p over HDMI so I know that the problem isn't my GPU. I was gifted this monitor but I can't use it to its full potential but I want to at least get 100hz @1080p. Is there something I am missing? I tried setting custom resolution with CRU and the Nvidia control panel as well as check under display adapter properties but only 60hz and 50hz are available. Overdrive is set to extreme, overclock is at 100. 

Kkings

I'm pretty sure you cannot go over 60hz with HDMI. Get a display port cable and use that input, should have no problem.