144hz Monitor stuck on 64hz with DP Cable

[ynpek]

So recently I just build a PC and was very hyped to use it and be able to run games consistently at 144FPS on 144hz. My monitor is 144hz and I am using a DisplayPort Cable. On my old PC I was easily successfully able to select 144hz in the Display Settings screen. But now, the only Hz amount that shows up is 64. I'm very disappointed and would love some help. If anyone knows how to fix this please help.

GPU: Gigabyte RTX 2070 Windforce OC
CPU: Intel Core i7-8700K
RAM: 16GB Trident Z G.Skill RGB 3200
PSU: 650W Corsair TX650M Gold Certified+
MONITOR: VG278Q 27" FULL HD 1080p 144hz 1ms Response Time

 

[vapour]

what are the old pc specs?
did you clean install or reuse the old OS?