Hi @Rishabh Choudhary!
You already have the latest firmware available for your modell. If you are locked to 144Hz, we recommend that you try updating your drivers for your graphics card and check that the video cable you are using supports 165Hz with the resolution you are using.
If you have done this and the problem is still the same, we recommend that you contact our customer support in the country where you purchased this monitor.
/Daniel
