jtchip wrote on 2025-12-21, 01:39:

Not necessarily, the earlier ones used a mux to switch the display outputs between the integrated and discrete GPUs. AIUI those […]
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myne wrote on 2025-12-20, 12:03:

All laptops since gpus were ever added do this.

Not necessarily, the earlier ones used a mux to switch the display outputs between the integrated and discrete GPUs. AIUI those made in the last 10-15 years, perhaps when PCIe bandwidth became sufficient so as to not cause a significant performance dip, switched to mux-less designs.

myne wrote on 2025-12-20, 12:03:

All it really is is copying the framebuffer from one card to another.

Indeed but it needs the drivers to have ability to do that. Easier to do that on a laptop with a fixed configuration and laptop vendor-supplied drivers but a potential nightmare on a desktop with any combination of devices and drivers.

In a sense this is a special case of ATI Crossfire where instead of sharing the rendering between 2 GPUs (one of which can even be integrated in the case of Hybrid Crossfire), one GPU does all of the rendering work.

afshin6760 wrote on 2025-12-20, 19:03:

After a little research, I found out that using this method with an iGPU is much more risky because many motherboards do not allow the simultaneous use of an iGPU and graphics.

It depends on the motherboard. Don't know about Windows but on Linux this combination has some use because the dGPU is disabled, and hence draws no power, when not in use and iGPUs have lower power draw at idle or light loads.

In any case, this thread really belongs on Milliways since an old secondary GPU that can do this really isn't that old. You should ask on other forums too.

Thanks, I’ve asked this on Milliways forum as well.

Don't dupe threads. You already have one for your issue.

Update: Success with RTX 4060 + i3-13100 + H610M-K (VGA Output)
​I wanted to confirm that you can use a modern dedicated GPU (like my RTX 4060) while keeping your monitor connected to the motherboard's VGA port. This is perfect for those using CRT monitors.
​How I did it:
​Plugged the CRT monitor directly into the motherboard's VGA port (using the i3-13100's iGPU).
​In Windows 11, I went to Settings > System > Display > Graphics.
​Under "Custom options for apps," I selected my games and set them to "High Performance" (NVIDIA GeForce RTX 4060).
​Result: The games render using the RTX 4060's power, but the frames are passed through the iGPU to the VGA output. It works flawlessly with no noticeable lag, and the image quality on my CRT is incredibly sharp!

afshin6760 wrote on 2026-02-03, 02:37:

Update: Success with RTX 4060 + i3-13100 + H610M-K (VGA Output) ​I wanted to confirm that you can use a modern dedicated GPU (li […]
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Update: Success with RTX 4060 + i3-13100 + H610M-K (VGA Output)
​I wanted to confirm that you can use a modern dedicated GPU (like my RTX 4060) while keeping your monitor connected to the motherboard's VGA port. This is perfect for those using CRT monitors.
​How I did it:
​Plugged the CRT monitor directly into the motherboard's VGA port (using the i3-13100's iGPU).
​In Windows 11, I went to Settings > System > Display > Graphics.
​Under "Custom options for apps," I selected my games and set them to "High Performance" (NVIDIA GeForce RTX 4060).
​Result: The games render using the RTX 4060's power, but the frames are passed through the iGPU to the VGA output. It works flawlessly with no noticeable lag, and the image quality on my CRT is incredibly sharp!

And before this, I had selected the igpu multi monitor and image output option in the bios and set its memory to 128mb.

afshin6760 wrote on 2026-02-03, 02:37:

Update: Success with RTX 4060 + i3-13100 + H610M-K (VGA Output) ​I wanted to confirm that you can use a modern dedicated GPU (li […]
Show full quote

Update: Success with RTX 4060 + i3-13100 + H610M-K (VGA Output)
​I wanted to confirm that you can use a modern dedicated GPU (like my RTX 4060) while keeping your monitor connected to the motherboard's VGA port. This is perfect for those using CRT monitors.
​How I did it:
​Plugged the CRT monitor directly into the motherboard's VGA port (using the i3-13100's iGPU).
​In Windows 11, I went to Settings > System > Display > Graphics.
​Under "Custom options for apps," I selected my games and set them to "High Performance" (NVIDIA GeForce RTX 4060).
​Result: The games render using the RTX 4060's power, but the frames are passed through the iGPU to the VGA output. It works flawlessly with no noticeable lag, and the image quality on my CRT is incredibly sharp!

Some DirectX games below 11 do not work with this method but do work using dgvoodoo.

afshin6760 wrote on 2025-12-19, 15:29:

Ozzuneoj wrote on 2025-12-19, 14:41:

afshin6760 wrote on 2025-12-19, 12:32:

On my old laptop, the NVIDIA 710M doesn’t actually output the display—Intel HD Graphics 2000 handles all the display tasks, both for the built-in screen and for a CRT, including EDID, refresh rate, resolution, and Vsync. I think the same thing should happen on a desktop setup using an older AMD GPU for the CRT while an RTX 5050 handles rendering.

Yes, that's common on laptops because they are built with that configuration in mind but on desktops using two discrete GPUs the situation is very different.

how about rtx 5050 and igpu ? (If the crt vga is connected to the motherboard) (and not using igpu to render the game )

That is a very similar setup to what my i5-3570K / GTX 1060 setup is doing.

One of the three monitors is connected to the integrated HD4000 through VGA, and I can easily move 3D-accelerated content onto it, while still rendering on the Geforce. With negligible performance impact.
The monitor on the iGPU isn't meant for anything demanding, just to display hardware monitoring and the occasional chat window, and the monitor is some old 1680x1050 thing I shot cheaply on ebay, but moving games onto it works just fine.

Not sure if there is any specific requirement regarding motherboard, OS or drivers, but it certainly works on desktop systems and running chips from different manufacturers.

For the easiest way to do this, I'd just grab a DisplayPort to VGA adapter like the Startech one I have and use the VGA monitor as a second screen. I did this with my RTX 3060 Ti and played Control on my 19" CRT; it looked pretty great and ran as smooth as butter at 1024x768 with DLAA. I probably could have run it at 1600x1200 if I wanted to, and I might just do that for fun with my 9070 XT if I can be bothered to drag the modern PC over to where my retro PC workdesk is.

Just be careful with VGA adapters.
Many don't support important resolutions like 720x400x70hz.
No post screen, no bios.