stuck resolution

Hello, So i got a new DP cable bc i broke the old one and now when i connect it i can change my resolution to 200hz but after a few seconds it comes back at 60hz i tried updating my GPU graphics and nothing worked. Can someone help me pls.

A few days ago my computer randomly froze and I had to turn it off. When I turned it back on it was stuck at 800x600 resolution, lagging, and I couldn't start any game without major issues/lag. My computer was unable to detect my monitor, and in device manager it showed a Code 43 error under my...