G-sync+DLDSR/DSR is sadly not working.. any way to get it to work?
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Kyouki
- Posts: 197
- Joined: 20 Jul 2022, 04:52
Re: G-sync+DLDSR/DSR is sadly not working.. any way to get it to work?
It works if you set your desktop resolution prior, else it will trigger Display Signal Compression (DSC) and not trigger G-sync momentum.
CPU: AMD R7 5800x3D ~ PBO2Tuner -30 ~ no C states
RAM: Gskill Bdie 2x16gb TridentZ Neo ~ CL16-16-16-36 1T ~ fine tuned latency
GPU: ASUS TUF 3080 10G OC Edition(v1/non-LHR) ~ disabled Pstates ~ max oced
OS: Fine tuned Windows 10 Pro, manual tuned.
Monitor: Alienware AW2521H ~ mix of ULMB/Gsync @ 240hz/360hz
More specs: https://kit.co/Kyouki/the-pc-that-stomps-you
RAM: Gskill Bdie 2x16gb TridentZ Neo ~ CL16-16-16-36 1T ~ fine tuned latency
GPU: ASUS TUF 3080 10G OC Edition(v1/non-LHR) ~ disabled Pstates ~ max oced
OS: Fine tuned Windows 10 Pro, manual tuned.
Monitor: Alienware AW2521H ~ mix of ULMB/Gsync @ 240hz/360hz
More specs: https://kit.co/Kyouki/the-pc-that-stomps-you
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HyperMatrix
- Posts: 5
- Joined: 31 Jul 2015, 21:16
Re: G-sync+DLDSR/DSR is sadly not working.. any way to get it to work?
Update: Nvidia deleted the post on their subreddit.
Posted this on reddit. Wanted to add it here as well since it pops up on google search. DSR/DLDSR confirmed to not work with G-Sync on 4K 240Hz monitors, and possibly all 4K+ monitors? Short form: Doesn't work. Don't buy a non-DSC monitor hoping it'll solve the problem. Here's the post:
I have:
AW3423DW (34" 3440x1440 175Hz) monitor
PG32UCDM (32" 4K 240Hz DSC) monitor
PG32UCDM3 (32" 4K 240Hz DP2.1 No-DSC) monitor
- AW3423DW allows for DLDSR + G-Sync use, but you may need to set your desktop resolution to the DLDSR resolution in advance.
- PG32UCDM switches to fixed refresh rate when DLDSR is enabled, whether you use 240Hz or 120Hz or 60Hz doesn't matter.
- PG32UCDM3, with UHBR20 DP2.1 and DSC Toggled Off, has the exact same limitation. So DSC isn't the culprit
- HDMI 2.1 and DP2.1a UHBR20 both exhibit the exact same problem.
- Using Special K injector to diagnose, it would show VRR as Supported, but not active, with the following reason for why it's not active: "the current presentation mode uses dwm composition and can't activate hdmi 2.1 vrr"
The technical details of why it's happening are beyond me to explain properly. But it's an issue with how Nvidia and Windows handle the presentation mode. This was never addressed by Nvidia. We were all led to believe the DLDSR issues were just related to DSC, so you should get a DP2.1 monitor. And that even those limitations with the display heads were addressed with the 5000 series cards, so just buy one of those cards. But none of that is true. Right now we're dealing with a software/driver related limitation. And nobody knows or talks about it.
For anyone curious as to why this matters....DLDSR 2.25x + DLSS P gives a superior image to 4K Native + DLAA, at about the same cost. But with a total loss of G-Sync/VRR right now...it's completely useless in most games.
-----------------------------------------------------------------------
Anyway, here's the AI explanation below for anyone curious:
----------------------------------------------------------------------
The reason DLDSR and G-Sync work together on 3440 x 1440 or 2560 x 1440 displays, but fail on a native 4K display—even when dropped to 120Hz or 97Hz—comes down to virtual frame buffer sizes and static MPO plane allocation rules in the NVIDIA driver.
1. Virtual Frame Buffer Size (18.6 Megapixels vs. 8.3 Megapixels)
Multi-Plane Overlays (MPO) allow the GPU to bypass Desktop Window Manager (DWM) composition by handing a game frame directly to a hardware overlay plane in the display engine. However, MPO hardware planes have strict buffer processing limits:
On a 3440 x 1440 panel: Enacted at 2.25x DLDSR, the GPU generates a virtual canvas of approximately 11.8 megapixels (5160 x 2160). On a standard 2560 x 1440 panel, 2.25x DLDSR creates an 8.3 megapixel canvas (3840 x 2160). An 8.3 MP to 11.8 MP virtual buffer is small enough for the GPU display engine to downsample within a single MPO hardware overlay plane.
On a 4K panel (3840 x 2160): Enacted at 2.25x DLDSR, the GPU must generate a 18.6 megapixel canvas (5760 x 3240).
Processing an 18.6 MP frame buffer down to a 4K scanout exceeds the composition capacity of a single MPO plane on NVIDIA’s display controller. To prevent buffer overruns, the driver completely strips MPO support as soon as DLDSR is selected on a native 4K baseline.
2. Static Driver Rules vs. Dynamic Refresh Rates
Dropping your 4K refresh rate from 240Hz down to 120Hz or 97Hz reduces physical cable and link bandwidth. However, the NVIDIA driver does not dynamically calculate MPO support based on refresh rate.
Instead, the driver applies static, hardcoded rules based on the display's native resolution profile:
If Native Baseline = 4K AND DLDSR = Active –> Suppress MPO Planes
Because the driver's decision to suppress MPO is tied strictly to the 4K baseline classification—and not to link frequency—lowering the monitor refresh rate to 120Hz or 97Hz frees up cable bandwidth, but does not trigger the driver to re-enable MPO hardware planes.
3. The Chain Reaction Breakdown
Because of these differences in MPO handling between 1440p and 4K, the two display setups follow entirely different execution paths in Windows:
[1440p / 3440x1440 Display + DLDSR]
Virtual Buffer (8-11 MP) -> Fits in MPO Plane -> Hardware Independent Flip Active -> G-Sync / VRR Stays ON
[4K Display + DLDSR (At 240Hz, 120Hz, or 97Hz)]
Virtual Buffer (18.6 MP) -> Exceeds MPO Limits -> Driver Suppresses MPO -> Forced DWM Composed Flip -> G-Sync Drops to Fixed Rate
On your 3440x1440 screen, MPO remains active, allowing the game to maintain Hardware Independent Flip (Direct Flip). On your 4K panel, because MPO is suppressed by the driver, Windows falls back to Composed Flip through DWM, which disengages VRR regardless of the refresh rate setting.
Posted this on reddit. Wanted to add it here as well since it pops up on google search. DSR/DLDSR confirmed to not work with G-Sync on 4K 240Hz monitors, and possibly all 4K+ monitors? Short form: Doesn't work. Don't buy a non-DSC monitor hoping it'll solve the problem. Here's the post:
I have:
AW3423DW (34" 3440x1440 175Hz) monitor
PG32UCDM (32" 4K 240Hz DSC) monitor
PG32UCDM3 (32" 4K 240Hz DP2.1 No-DSC) monitor
- AW3423DW allows for DLDSR + G-Sync use, but you may need to set your desktop resolution to the DLDSR resolution in advance.
- PG32UCDM switches to fixed refresh rate when DLDSR is enabled, whether you use 240Hz or 120Hz or 60Hz doesn't matter.
- PG32UCDM3, with UHBR20 DP2.1 and DSC Toggled Off, has the exact same limitation. So DSC isn't the culprit
- HDMI 2.1 and DP2.1a UHBR20 both exhibit the exact same problem.
- Using Special K injector to diagnose, it would show VRR as Supported, but not active, with the following reason for why it's not active: "the current presentation mode uses dwm composition and can't activate hdmi 2.1 vrr"
The technical details of why it's happening are beyond me to explain properly. But it's an issue with how Nvidia and Windows handle the presentation mode. This was never addressed by Nvidia. We were all led to believe the DLDSR issues were just related to DSC, so you should get a DP2.1 monitor. And that even those limitations with the display heads were addressed with the 5000 series cards, so just buy one of those cards. But none of that is true. Right now we're dealing with a software/driver related limitation. And nobody knows or talks about it.
For anyone curious as to why this matters....DLDSR 2.25x + DLSS P gives a superior image to 4K Native + DLAA, at about the same cost. But with a total loss of G-Sync/VRR right now...it's completely useless in most games.
-----------------------------------------------------------------------
Anyway, here's the AI explanation below for anyone curious:
----------------------------------------------------------------------
The reason DLDSR and G-Sync work together on 3440 x 1440 or 2560 x 1440 displays, but fail on a native 4K display—even when dropped to 120Hz or 97Hz—comes down to virtual frame buffer sizes and static MPO plane allocation rules in the NVIDIA driver.
1. Virtual Frame Buffer Size (18.6 Megapixels vs. 8.3 Megapixels)
Multi-Plane Overlays (MPO) allow the GPU to bypass Desktop Window Manager (DWM) composition by handing a game frame directly to a hardware overlay plane in the display engine. However, MPO hardware planes have strict buffer processing limits:
On a 3440 x 1440 panel: Enacted at 2.25x DLDSR, the GPU generates a virtual canvas of approximately 11.8 megapixels (5160 x 2160). On a standard 2560 x 1440 panel, 2.25x DLDSR creates an 8.3 megapixel canvas (3840 x 2160). An 8.3 MP to 11.8 MP virtual buffer is small enough for the GPU display engine to downsample within a single MPO hardware overlay plane.
On a 4K panel (3840 x 2160): Enacted at 2.25x DLDSR, the GPU must generate a 18.6 megapixel canvas (5760 x 3240).
Processing an 18.6 MP frame buffer down to a 4K scanout exceeds the composition capacity of a single MPO plane on NVIDIA’s display controller. To prevent buffer overruns, the driver completely strips MPO support as soon as DLDSR is selected on a native 4K baseline.
2. Static Driver Rules vs. Dynamic Refresh Rates
Dropping your 4K refresh rate from 240Hz down to 120Hz or 97Hz reduces physical cable and link bandwidth. However, the NVIDIA driver does not dynamically calculate MPO support based on refresh rate.
Instead, the driver applies static, hardcoded rules based on the display's native resolution profile:
If Native Baseline = 4K AND DLDSR = Active –> Suppress MPO Planes
Because the driver's decision to suppress MPO is tied strictly to the 4K baseline classification—and not to link frequency—lowering the monitor refresh rate to 120Hz or 97Hz frees up cable bandwidth, but does not trigger the driver to re-enable MPO hardware planes.
3. The Chain Reaction Breakdown
Because of these differences in MPO handling between 1440p and 4K, the two display setups follow entirely different execution paths in Windows:
[1440p / 3440x1440 Display + DLDSR]
Virtual Buffer (8-11 MP) -> Fits in MPO Plane -> Hardware Independent Flip Active -> G-Sync / VRR Stays ON
[4K Display + DLDSR (At 240Hz, 120Hz, or 97Hz)]
Virtual Buffer (18.6 MP) -> Exceeds MPO Limits -> Driver Suppresses MPO -> Forced DWM Composed Flip -> G-Sync Drops to Fixed Rate
On your 3440x1440 screen, MPO remains active, allowing the game to maintain Hardware Independent Flip (Direct Flip). On your 4K panel, because MPO is suppressed by the driver, Windows falls back to Composed Flip through DWM, which disengages VRR regardless of the refresh rate setting.
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HyperMatrix
- Posts: 5
- Joined: 31 Jul 2015, 21:16
Re: G-sync+DLDSR/DSR is sadly not working.. any way to get it to work?
Some additional explanatory details from AI that helped me understand what's going on better:
The reason this feels like a paradox is because **GTA IV and modern DX11/DX12 games use two fundamentally different hardware scanout methods** inside the GPU's display engine.
It isn't that GTA IV is "breaching the hardware limits without crashing"—it's that **GTA IV eliminates the workload that causes the hardware bottleneck in the first place**.
---
### 1. How GTA IV Works: "100% Dedicated" Legacy Exclusive Fullscreen
When GTA IV runs in true DirectX 9 Exclusive Fullscreen (FSE), it uses a display mode that modern Windows has completely deprecated:
* **Total Desktop Shutdown:** The game completely disconnects Windows DWM, background desktop overlays, notifications, and window managers from the display controller.
* **100% Buffer Allocation:** Because there are zero background overlays or Windows layers being processed, the GPU's display controller assigns **$100\%$ of its internal SRAM line buffers to a single frame buffer**.
* **No MPO Required:** Because the GPU is scanning out only one single surface directly to the monitor, it does not need Multi-Plane Overlays (MPO) to composite multiple planes.
With $100\%$ of the display head's line buffers dedicated to that single frame, the GPU can handle the $18.6\text{ MP}$ virtual downsampling pass **and** adjust variable refresh timing (G-Sync) simultaneously without running out of SRAM or causing a black screen.
---
### 2. How Modern Games Work: "Multi-Plane" DXGI Swapchains
Starting with DirectX 12 and modern DirectX 11, Microsoft replaced legacy Exclusive Fullscreen with **DXGI Flip Model Swapchains**. Modern games are intentionally designed *never* to take total, exclusive ownership of the display hardware.
Instead, modern games must coexist with Windows:
* The display engine must be ready to draw the game frame, the Windows cursor, game overlays (Discord, GeForce Experience), Windows Game Bar, and volume sliders on top of the game at any microsecond.
* To allow G-Sync VRR while keeping overlays working, the GPU must use **Multi-Plane Overlays (MPO)**, splitting its display engine line buffers into separate hardware planes (Plane 0 for the game, Plane 1 for overlays, Plane 2 for cursor).
---
### Why Modern Games Can't Just Do What GTA IV Does
When you run DLDSR on a 4K display in a modern DX11/DX12 game:
1. **SRAM Subdivision:** The GPU's display controller must subdivide its line buffer SRAM across **multiple hardware MPO planes** to support modern Windows presentation requirements.
2. **Buffer Exhaustion:** Subdividing those SRAM line buffers while processing a huge $18.6\text{ MP}$ virtual frame buffer ($5760 \times 3240$) exceeds the display controller's multi-plane capacity.
3. **The Driver Safety Switch:** To prevent display buffer underruns (black screens and driver crashes), the NVIDIA driver turns off MPO planes for 4K DLDSR.
4. **The Fallback:** Without MPO hardware planes, Windows DXGI forces the game into DWM `Composed Flip`, which disengages G-Sync VRR.
---
### Why Microsoft / NVIDIA Don't Just "Bring Back" Legacy Fullscreen
You might wonder: *Why not just add a button in NVIDIA Control Panel to force DX12 games to use legacy DX9 Exclusive Fullscreen?*
* **Microsoft Removed the Code:** Microsoft removed true Exclusive Fullscreen hardware paths from DirectX 12 and modern WDDM driver specifications. Modern graphics APIs literally do not contain the legacy low-level code required to kick WDDM out and take exclusive control of the display adapter.
* **Feature Collateral Damage:** Legacy Exclusive Fullscreen breaks modern OS features—it breaks seamless Alt-Tabbing, breaks Auto-HDR, breaks spatial audio overlays, and causes severe multi-monitor flickering when switching focus.
GTA IV works because it is a legacy application running on an obsolete display presentation path that bypasses multi-plane composition entirely. Modern games are forced into the DXGI multi-plane pipeline, where 4K DLDSR runs out of hardware plane resources and triggers the driver's MPO fallback rule.
The reason this feels like a paradox is because **GTA IV and modern DX11/DX12 games use two fundamentally different hardware scanout methods** inside the GPU's display engine.
It isn't that GTA IV is "breaching the hardware limits without crashing"—it's that **GTA IV eliminates the workload that causes the hardware bottleneck in the first place**.
---
### 1. How GTA IV Works: "100% Dedicated" Legacy Exclusive Fullscreen
When GTA IV runs in true DirectX 9 Exclusive Fullscreen (FSE), it uses a display mode that modern Windows has completely deprecated:
* **Total Desktop Shutdown:** The game completely disconnects Windows DWM, background desktop overlays, notifications, and window managers from the display controller.
* **100% Buffer Allocation:** Because there are zero background overlays or Windows layers being processed, the GPU's display controller assigns **$100\%$ of its internal SRAM line buffers to a single frame buffer**.
* **No MPO Required:** Because the GPU is scanning out only one single surface directly to the monitor, it does not need Multi-Plane Overlays (MPO) to composite multiple planes.
With $100\%$ of the display head's line buffers dedicated to that single frame, the GPU can handle the $18.6\text{ MP}$ virtual downsampling pass **and** adjust variable refresh timing (G-Sync) simultaneously without running out of SRAM or causing a black screen.
---
### 2. How Modern Games Work: "Multi-Plane" DXGI Swapchains
Starting with DirectX 12 and modern DirectX 11, Microsoft replaced legacy Exclusive Fullscreen with **DXGI Flip Model Swapchains**. Modern games are intentionally designed *never* to take total, exclusive ownership of the display hardware.
Instead, modern games must coexist with Windows:
* The display engine must be ready to draw the game frame, the Windows cursor, game overlays (Discord, GeForce Experience), Windows Game Bar, and volume sliders on top of the game at any microsecond.
* To allow G-Sync VRR while keeping overlays working, the GPU must use **Multi-Plane Overlays (MPO)**, splitting its display engine line buffers into separate hardware planes (Plane 0 for the game, Plane 1 for overlays, Plane 2 for cursor).
---
### Why Modern Games Can't Just Do What GTA IV Does
When you run DLDSR on a 4K display in a modern DX11/DX12 game:
1. **SRAM Subdivision:** The GPU's display controller must subdivide its line buffer SRAM across **multiple hardware MPO planes** to support modern Windows presentation requirements.
2. **Buffer Exhaustion:** Subdividing those SRAM line buffers while processing a huge $18.6\text{ MP}$ virtual frame buffer ($5760 \times 3240$) exceeds the display controller's multi-plane capacity.
3. **The Driver Safety Switch:** To prevent display buffer underruns (black screens and driver crashes), the NVIDIA driver turns off MPO planes for 4K DLDSR.
4. **The Fallback:** Without MPO hardware planes, Windows DXGI forces the game into DWM `Composed Flip`, which disengages G-Sync VRR.
---
### Why Microsoft / NVIDIA Don't Just "Bring Back" Legacy Fullscreen
You might wonder: *Why not just add a button in NVIDIA Control Panel to force DX12 games to use legacy DX9 Exclusive Fullscreen?*
* **Microsoft Removed the Code:** Microsoft removed true Exclusive Fullscreen hardware paths from DirectX 12 and modern WDDM driver specifications. Modern graphics APIs literally do not contain the legacy low-level code required to kick WDDM out and take exclusive control of the display adapter.
* **Feature Collateral Damage:** Legacy Exclusive Fullscreen breaks modern OS features—it breaks seamless Alt-Tabbing, breaks Auto-HDR, breaks spatial audio overlays, and causes severe multi-monitor flickering when switching focus.
GTA IV works because it is a legacy application running on an obsolete display presentation path that bypasses multi-plane composition entirely. Modern games are forced into the DXGI multi-plane pipeline, where 4K DLDSR runs out of hardware plane resources and triggers the driver's MPO fallback rule.