I'm extremely new to > 60Hz gaming and i was wondering what i'm doing incorrect.
I recently bought the PG278QR. Its the first moniter ive ever had over 1080p and 60Hz, I'm using it along side my VS248H-P (Not sure if that matters because the issue persists even with only the PG278QR connected.

Basically the issue is every game is restricted to 120fps, no matter the game/engine/settings/Nvidia Settings. Due to my inexperience i cant tell if the Desktop/General Refresh rate is locked to 120Hz, but its 100% higher than 60Hz.

This is My PC

Things I've tried include:

• Using an aftermarket DP 1.4 cable rated for 1440p @ 165hz
  
• Using the Stock DP Cable included in the box (I belive its DP 1.2?)
  
• Enable G-Sync/Disable G-Sync
  
• Enable/Disable VSync
  
• Lowering the Resolution
  
• Switching the monitor off of 165Hz then back on.
  
• Resetting the monitor in the OSD and re-overclocking it to 165Hz.
  
• Moving the game to my 60Hz monitor (Which actully unlocks the framerate when set to do so)
  
• Reinstalling the Drivers for Nvidia (Version 398.36)
  
• Updating to the latest Windows 10 Build (Version 1803 Build 17134.165)
  

Games I've tested

• Skyrim Special Edition
  
• Fallout 4
  
• Payday 2
  
• GTA: V
  
• Oblivion
  
• Minecraft
  
• Far Cry 5
  
• Arma 3
  
• Forza Motorsport 7
  
• Garry's Mod
  
• Battlefield 1
  

Here's a few more maybe useful screenshots.
dxdiag
Nvidia Control Panel Settings
Windows 10 Advanced Display Settings
OSD Settings (Sorry for the Exposure)

This is my first post on these forums, if I'm missing any information or posting this in the wrong place i apologize. Thanks for taking the time to help me, let me know if any further information is needed.