Retroarch not working in 240p?

[Stremon]

Hey guys,

So on my config (AMD HD5770 in Windows 10 x64 with a PC CRT), I managed to make groovymame work flawlessly in 240p/120Hz, but I failed to make retroarch work.

Of course I activated the CRT SwitchRes function inside retroarch, along with the option to double the frequency to 120Hz.
But no matter what I do, retroarch doesn't want to display anything lower than 640*480.
I even added all super resolutions shown in the github help, but still no change.
For the display driver used by retroarch, I tried d3d9, d3d10 and d3d11, they all give me different results (240p taking only half of the screen, or 480p), but none work.

I spent hours to search online how to make it work to be sure I don't ask for help for nothing. I tried all the solutions I found, none work.
To me it looks like retroarch only want to switch to resolutions that appear in the Windows 10 display settings, and indeed the custom resolutions created by VMMaker don't appear there.

Did any of you guys managed to make it work? what do you think could be my issue?
Thanks 

[Yuke]

Hey cant help you specifically but i remember having the same problems with Windows10 and Retroarch (no resi switching and everything was crushed to the left side of the screen)....only solution i found was to switch to Win7....bought a key for 3 euro on ebay.

Its a problem with older graphicscards from what ive been told on the official Retroarch board. A guy with a R9 AMD graphicscard never had problems with Win10.

[Stremon]

So that's very strange, after doing many tests during extensive weeks, rebooting my pc and all, just after I wrote this message, the 120Hz stopped working in groovymame too.
Then I reinstalled the custom resolution, and now it works on everything, including retroarch and the other emulators!
I just have no idea on how and why it happened... a missing windows update maybe? 

Edit: And I was right, the problem was that the custom resolutions couldn't be seen by windows.
Now I can see them.
So to anyone who has the same issue, check the windows graphic settings for those.

[zerochad]

I wrote a guide for this (sorta) exact problem, barely any info on how to get RetroArch working on a CRT aside from like bits and pieces from forums

https://cdcruze.com/2019/03/retroarch-and-crt-emudriver-setup-guide/

[Torro14]

You can see the super resolutions selectable in the windows graphics settings?

I followed the guide above, and the only resolution I can see there is 640x480 greyed out....