- Apr 5, 2016
- GIGABYTE Z170X-Gaming 7
- GTX TITAN X
- , , , , ,
- Classic Mac
- , ,
- Mobile Phone
Since you have a 4K display, make sure that "Scaled resolution base" is set to 3840 x 2160. This seems to be the case already, as you are able to select 1920x1080@120hz HiDPI - but check SwitchResX to verify that the timing used by that resolution is 3840x2160@120Hz. Actually, I am curious to see a screenshot of the timing info from SwitchResX, as 4K120Hz is near limit of 8 bit color DisplayPort 1.4 without display stream compression. I would like to know if the timing differs from the CVT-RB calculation of SwitchResX.I have an Acer XV273K (4K / 120hz), and am able to select 3840x2160@120hz and 1920x1080@120hz HiDPI and everything works correctly. However, for the other intermediate scaling options like "Looks like 2560x1440", I can only select 60hz refresh rate.
I've tried creating custom resolutions in SwitchResX but I can't create anything that's not a 2x resolution. I've seen the guides for DisplayOverrides but they always mention creating 2x resolutions too... not something in between like I'm trying to use here. Any tips?
For "Looks like 2560x1440" you need to create a custom resolution that is a scaled resolution of 5120x2880.
After that, since you are able to select 1920x1080@120Hz HiDPI, you should now be able to select 2560x1440@HiDPI also (they should both use the 3840x2160@120Hz timing).
I am unable to find a method that results in multiple refresh rates for a scaled timing. For example, I can create several 4K timings (30Hz, 40Hz, 50 Hz, 60Hz) and a 5K scaled resolution, but the scaled resolution uses only one of the 4K timings (the one with the lowest refresh rate). This is probably a limitation of Apple's graphics drivers.