forcing/changing refresh rates for PC CRTs with VGA?

[creamblast]

So I'm looking at PC CRT monitors again, I used one up until 2014 until I moved. They were/are really good for games like Quake and Counter strike still and online fighters but since I'm kind of getting back into dreamcast mainly for the quality of the FG ports on it I'd like to know is it possible to set a refresh rate above 60 hz?

and please before anyone comments about framerate and refresh not mattering if the fps isn't high enough. it definitely does, and it significantly reduces eye strain. I don't want to have a debate/discussion regarding that. I'd just like to know if its possible to set a higher refresh rate since I assume it outputs and/or sets a display resolution of 640x480, and the nicer ones can go up to 140hz or more at that display resolution when used on a PC.

[hypnoticsinglet]

I think the later improvement was aimed at improving good speed performancegeometry dash lite. Programs that run reliably need large enough storage capacity to ensure best performance.

[TapamN]

So I'm looking at PC CRT monitors again, I used one up until 2014 until I moved. They were/are really good for games like Quake and Counter strike still and online fighters but since I'm kind of getting back into dreamcast mainly for the quality of the FG ports on it I'd like to know is it possible to set a refresh rate above 60 hz?

and please before anyone comments about framerate and refresh not mattering if the fps isn't high enough. it definitely does, and it significantly reduces eye strain. I don't want to have a debate/discussion regarding that. I'd just like to know if its possible to set a higher refresh rate since I assume it outputs and/or sets a display resolution of 640x480, and the nicer ones can go up to 140hz or more at that display resolution when used on a PC.

Not really, the pixel clock on the DC doesn't go high enough for higher refresh rates, at least not without reducing the resolution.

I guess it would be possible to hack low resolution games to output 120 hz, which is something I did by accident while patching KoF 98 to support VGA (https://imgur.com/a/AHmbM8v - Watch for the OSD at the top of the screen around the 0:27 mark), but most games (especially low res 2D games) tie the game speed to the refresh rate, so you'd also have to hack the game to run at "half speed"/normal speed. In that link, KoF 98 is running at double speed due to the doubled framerate; I did not speed up the video. It would be possible to fix that half the screen being cut off, that's just from the messed up attempt at a VGA patch.

I've done experiments with 120 hz for homebrew, and there are two ways to do 120 hz on the DC. One gives you scanlines, like 240p on a TV (it outputs a 640x240 120hz signal), and the other (320x480 120hz signal) lacks the scanlines, but the image is smeared somewhat horizontally. Both modes can still work fine with a 320x240 framebuffer, since the DC has a pixel/line doubler to output a 320x240 on it's normal 640x480 VGA signal.

One mode that the hardware can do well is 640x400 70hz VGA, but fixing the game speed would be harder, and almost impossible to do so without bad judder on any game that isn't a PC port. Plus, you'd have some of the display cut off (or have to deal with bad downscaling+slowdown), so it's not a good option. But 640x400x70 is handy for homebrew DOS emulation, ScummVM, or Doom.