3840x2160@134Hz in "Detailed resolution" section of CRU

[YavorS]

My new monitor is Acer XV273K and my current video card is GTX 1080, connected by DisplayPort 1.4 cable. My goal with the CRU is to set default resolution in "Detailed resolution" section to the tested and working overclocked resolution of 3840x2160@134Hz (tested and set in Windows 10 by "Nvidia Control Panel" function: "Create costume resolution").

This are the working resolution settings that I want to set as default resolution in the "Detailed resolution" of CRU:

   

The problem is when I delete all the default settings from CRU "Detailed resolution", which are:

   

and try to add the exact setting from the "Nvidia Control Panel" function: "Create costume resolution" for the 3840x2160@134Hz resolution, CRU won’t let my (there is red text and the "OK" button is unavailable):

   

Apparently, there is something that I missing from the configuration, but I spend hours trying with no luck. So I decide to register in this forum and to ask. I suspect that the problem is somewhere in this settings, but they are beyond my understanding:

       

[ToastyX]

To add a resolution greater than 655.35 MHz pixel clock, you have to add it in a DisplayID extension block. The "Default extension block" is probably a DisplayID extension block, but NVIDIA's driver doesn't provide the information to CRU for some reason. You have to delete it and add one manually. That's probably where 3840x2160 @ 120 Hz is defined by default. Anything beyond 1080 MHz pixel clock would require either 6 bpc color or display stream compression, so I'm not sure what will happen when you add 3840x2160 @ 134 Hz. The monitor itself has an option in the menus to enable 3840x2160 @ 144 Hz without needing to add a custom resolution, but the manual says it only works with AMD GPUs.

[YavorS]

Thank you! This clears the thing a lot for me! I didn't realize that the "working" custom resolution of 3840x2160@134Hz in fact is 6 bpc color. But in the end, I achieved what I want: to have only one resolution of 3840x2160 with the best possible refresh rates (some games just switched to this low frame rates versions of the 3840x2160, without possible way to increase it to 120Hz). I delete all unwanted resolutions, delete the original "Default extension block", create new one with DisplayID - 3840x2160@120Hz and everything just work now. Thank you!