G-SYNC not working in borderless fullscreen source games

Talk about NVIDIA G-SYNC, a variable refresh rate (VRR) technology. G-SYNC eliminates stutters, tearing, and reduces input lag. List of G-SYNC Monitors.
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foobar2000
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G-SYNC not working in borderless fullscreen source games

Post by foobar2000 » 16 Jul 2026, 19:18

In source games like left 4 dead 2, garry's mod etc. G-SYNC doesn't work on my laptop and my desktop when in borderless fullscreen mode. When I switch to fullscreen mode it works, and normally I would just set it to fullscreen mode but I need to have garry's mod in borderless fullscreen for a certain mod to work properly, so I'm wondering what a fix could be.

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RealNC
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Re: G-SYNC not working in borderless fullscreen source games

Post by RealNC » 17 Jul 2026, 02:41

Older DX10 and DX11 games that don't make use of independent flip frame presentation need to be promoted to independent flip. On Windows 11, you should enable "optimization for windowed games":

https://support.microsoft.com/en-US/Win ... windows-11

For DX9 games, you can't do anything without translating them to DX11/12/Vulkan. They require exclusive fullscreen as it's not possible to use modern frame presentation models with DX9. You need to use a wrapper/translation layer to convert them to DX11/DX12 (with dgVoodoo 2, but it's slow), or to Vulkan (with DXVK, this is much faster.)

Personally, I use dgVoodoo 2 for very old games where I want to force SGSSAA for anti aliasing in nvidia profile inspector. For not-so-old DX9 games where you can't force AA anyway and also run too slow with dgV, I use DXVK instead.
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vlad54rus
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Re: G-SYNC not working in borderless fullscreen source games

Post by vlad54rus » 19 Jul 2026, 03:48

RealNC wrote:
17 Jul 2026, 02:41
For DX9 games, you can't do anything without translating them to DX11/12/Vulkan. They require exclusive fullscreen as it's not possible to use modern frame presentation models with DX9
It's possible to patch D3D9 to force flip model in windowed modes (source). I myself have been using this method to play Left 4 Dead 2 and Fallout 3 in borderless windowed.

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RealNC
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Re: G-SYNC not working in borderless fullscreen source games

Post by RealNC » Yesterday, 08:54

vlad54rus wrote:
19 Jul 2026, 03:48
It's possible to patch D3D9 to force flip model in windowed modes (source). I myself have been using this method to play Left 4 Dead 2 and Fallout 3 in borderless windowed.
I assume these are per-game mods, not something generic you can do with every game?
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vlad54rus
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Re: G-SYNC not working in borderless fullscreen source games

Post by vlad54rus » Yesterday, 11:01

RealNC wrote:
Yesterday, 08:54
vlad54rus wrote:
19 Jul 2026, 03:48
It's possible to patch D3D9 to force flip model in windowed modes (source). I myself have been using this method to play Left 4 Dead 2 and Fallout 3 in borderless windowed.
I assume these are per-game mods, not something generic you can do with every game?
The patch itself isn't game specific. In my case all I had to do is to nop-out 7 bytes in d3d9.dll (the one in C:\Windows\SysWOW64 folder).

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RealNC
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Re: G-SYNC not working in borderless fullscreen source games

Post by RealNC » Yesterday, 13:48

vlad54rus wrote:
Yesterday, 11:01
The patch itself isn't game specific. In my case all I had to do is to nop-out 7 bytes in d3d9.dll (the one in C:\Windows\SysWOW64 folder).
And it's not blocked from loading due to non-matching digital signature?
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vlad54rus
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Re: G-SYNC not working in borderless fullscreen source games

Post by vlad54rus » Today, 00:26

RealNC wrote:
Yesterday, 13:48
And it's not blocked from loading due to non-matching digital signature?
Nope

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