Problem with monitor and screen resolutions

Hello everyone,

i've changed the screen resolution to 1600x1050 @60 HZ, but OS4 doesn't boot up in workbench anymore.

There is a quick way to rebert back to the old resolution?

Thank you

Boot with no startup-sequence and delete your screenmode.prefs from ENVARC:sys

Simon

@Rigo
done, thank you.

My monitor support 1600x1050, but doesn't work in OS4.

@AmigaBlitter

deleted screenmode.prefs, but still not work

Which machine and graphics card are you using?

Which resolution did you sucessfully use before?

Best regards,

Niels

I have the Sam440ep, with integrated radeon M9.
After several tries i managed to set the video resolution to 1600x1050@60 hz. Notice that even after tried with lower res, the system wasn't able to boot to workbench. I could hear the startup jingle only with no video on screen.

Try to put the resolution at 70hz..

Also try adding +RB to the mode.

And make sure you use the VGA output, it yields a higher pixelclock than DVI.

Best regards,

Niels

PS: If my suspicion is right, and the resolution requires a higher pixelclock than available, I don't think nubechecorre's suggestion of increasing one of the frequencies is going to help, as that will increase the total pixelclock requirements even more.

But do try it, I may be wrong about the cause.

@AmigaBlitter

I own a monitor that supports 2560x1440 max.

When i let screenmode prefs do the setting, that specific screenmode won't work, the screen will stay black.

After much struggling i tuned down the frequency setting from 60Hz to 56Hz and et voila it works.

Problem is, that screenmode prefs still persists on 60 Hz (if i use the automatic setting) so i had to change it manually in the monitor file's tooltypes:

MODE=2560x1440@56

Screenmode prefs "incorrectly" reports it as 57Hz and all the 60Hz modes as 61Hz so i see a bug in the prefs program.

Try to manually change your setting to 55 Hz, reboot, see if that works and move up to the closet setting that works for you.

If it's not too late you might be able to fetch an older screenmode.prefs out of SYS:.recycled/

I have a similar problem.





I have a Samsung U28D590 UHD monitor connected to my Amiga X1000 with a Radeon R9-270X gfx card.

I can't remember the circumstances, but i've ran 3840x2160 on this amiga/monitor before, but if i remember correctly, it then booted into this resolution automatically one day i started it.

3840x2160 is a bit high, but i want to run 2560x1440, even though this is not the default resolution for this monitor. It's still good. But as the attatched pics show, the screen becomes kind of "compressed" horizontally" when i tes/use this res.

However, and this is weird.... If i use SGrab to grab a screenshot of the testing screen and view it in multiviewer afterwards, select 1:1 display, it shows up correct!

A similar situation, is when i sometimes play a video in mplayer fullscreen, i get the same horizontal "squished" effect, but if i sblclick on the screen to view the video in a window, it becomes correct.

This tells me i lack some pixelwidth horizontally, or the horizonlal sync is too large or something.

Anyone know how i can get this to work? I've registered the RadeonHD drivers. Also, i get the same no matter if i use DVI->HDMI or plain HDMI.

@Shamron

Your screenshots look typical of a screen mode running in dual-link DVI mode with a monitor/cable that is only single-link capable.

You could try checking if your monitor is dual-link capable. If it is, make sure that you have a dual-link DVI cable, or half the pixels on your screen will be missing.

We do have an added complication. The newer HDMI specification versions have more than doubled the maximum allowable pixel clock on a single-link. Some newer monitors are single-link only and support UHD resolutions using the increased max pixel clock. Unfortunately, the only way to know if a monitor supports the higher frequencies is to read the EDID data (from DDC). Currently, the graphics driver has no way to extract this info. So, it always switches to dual-link mode if the pixel clock exceeds the original maximum of 165 MHz.

Hans