Monitors which convert image to 60Hz

mark_k · 12 April 2017, 21:56

Is it common for modern LCD monitors to always convert the input video signal refresh rate to 60Hz?

I received an Acer CB241HQK monitor recently (3840×2160 60Hz). It works fine with that signal input to it. But if I set my PC to output at 50Hz (better for WinUAE & PAL Amiga demos etc.), while the monitor accepts and displays that and its OSD says 50Hz, it seems the LCD is actually being refreshed at 60Hz.

Running a PAL demo in WinUAE with vsync on, which should give very smooth scrolling, doesn't. Scrolling is slightly juddery, consistent with every 5th frame being duplicated.

I guess my next monitor upgrade will be to a FreeSync-capable model which will definitely give a true 50Hz display...

Toni Wilen · 12 April 2017, 22:06

It does not have HDMI2 so it is not designed to be any kind of "media" display, no guarantee for proper 50Hz support. Perhaps it only works in 1080p resolution?

mark_k · 12 April 2017, 22:43

Nope, with 1080p50 input the LCD still seems to refresh at 60Hz.

I tried forcing EDID emulation in the AMD video driver to output 3840×2160 at 50Hz, first by reducing the pixel clock, then by keeping the original pixel clock but increasing the number of vertical blanking lines. Same result both ways.

12 April 2017, 21:56	#1
mark_k Registered User Join Date: Aug 2004 Location: Posts: 3,346	Monitors which convert image to 60Hz Is it common for modern LCD monitors to always convert the input video signal refresh rate to 60Hz? I received an Acer CB241HQK monitor recently (3840×2160 60Hz). It works fine with that signal input to it. But if I set my PC to output at 50Hz (better for WinUAE & PAL Amiga demos etc.), while the monitor accepts and displays that and its OSD says 50Hz, it seems the LCD is actually being refreshed at 60Hz. Running a PAL demo in WinUAE with vsync on, which should give very smooth scrolling, doesn't. Scrolling is slightly juddery, consistent with every 5th frame being duplicated. I guess my next monitor upgrade will be to a FreeSync-capable model which will definitely give a true 50Hz display...

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12 April 2017, 22:06	#2
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,536	It does not have HDMI2 so it is not designed to be any kind of "media" display, no guarantee for proper 50Hz support. Perhaps it only works in 1080p resolution?

12 April 2017, 22:43	#3
mark_k Registered User Join Date: Aug 2004 Location: Posts: 3,346	Nope, with 1080p50 input the LCD still seems to refresh at 60Hz. I tried forcing EDID emulation in the AMD video driver to output 3840×2160 at 50Hz, first by reducing the pixel clock, then by keeping the original pixel clock but increasing the number of vertical blanking lines. Same result both ways.

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