@casperes1996 - yes, seems it was something of the kind you are describing. I will re-test tomorrow with the supposedly better cable. Also after the "crash" I tried to boot in safe and recovery mode, and it was a no go - black screen. Then used single user mode and deleted the display override to be able to boot normally.
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Mac mini 2014 monitor dilema - UHD vs QHD
- Thread starter vddobrev
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Update: I have settled for 1920x1080@30Hz (HiDPI) at which the Dell P2715Q excels. It is not that bad actually, and it is quite usable for my purposes. I moved the monitor further away and in fact the 1920x1080 helps my eyes compared to 2560x1440 as I have a prescription -0.75 diopters but I don't like wearing glasses in front of the computer.
All-in-all, naturally I would prefer 60Hz refresh rate, but this solution with a Mac mini and Dell P2715Q at 1920x1080@30Hz is a good and working stop-gap solution until the next Mac mini is released or I decide to buy a Mac Pro.
All-in-all, naturally I would prefer 60Hz refresh rate, but this solution with a Mac mini and Dell P2715Q at 1920x1080@30Hz is a good and working stop-gap solution until the next Mac mini is released or I decide to buy a Mac Pro.
Could it be that the iGPU can't upsample beyond 4k? Apple's HiDPI 2560x1440 on a 3840x2160 screen is gotten, if I understand correctrly, by doubling 2560x1440 and then downsampling to 4k. That's why 1920x1080 HiDPI is possible (as no additional downsampling is needed) as well as native 4k of course. I'm guessing that a 4k iMac could give more (intermediate) scaling options as the iGPU or dGPU are more powerful. Same for 5k iMacs. Just a thought.
You're correct in how the resolution is gotten, but I don't think the issue is as such. The GPU would have to render a 5120x2880 image in its frame buffer, but it would only have to output the 4k image to the display - The GPU is fully capable of outputting 4k (as we of course see), so the limitation there could be would have to be in rendering the 5120x2880 image in the frame buffer - that also seems unlikely to me, as all GPUs should be able to do this, however, not necessarily do it fast enough for it to run smooth. Apple may have put in the limitation after testing that it runs like balls on these GPUs, but performance issues aside, it should be possible
Must be the difference between your Iris 6100 and the MM 2014's (and MBP 13" 2013/14's) Iris 5100. That may also explain why the MBP 2015 13" can drive ext monitor @60Hz.
One good thing - I am able to control the Dell P2715Q brightness with this app https://github.com/Bensge/NativeDisplayBrightness using fn+F1 and fn+F2. Just build with XCode, copy in Applications, and add to login items.
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Indeed.