RTSS (RivaTuner): Best Global.cfg for Perfect Frame Rate Limiting

The Global.cfg file controls the core timing behavior of the RTSS injector. By default, it uses “Async” limiting, which is smooth but adds roughly one frame of lag. To minimize this, we transition to Reflex or Front-Edge Sync modes.

File Path

The global configuration is hidden in the RTSS installation directory. You must run your text editor (Notepad++) as Administrator to save changes.

C:\Program Files (x86)\RivaTuner Statistics Server\Profiles\Global.cfg

Technical Note: If you want these settings to apply only to a specific game (e.g., CS2 or Warzone), create a dedicated profile in the same folder named [GameEXE].cfg and copy these values there.

Optimized “Flatline” Configuration Table

Parameter	Recommended Value	Technical Purpose
FramerateLimitMode	2	Reflex Mode. Injects NVIDIA/AMD-style low-latency capping.
SyncTimeout	1	Forces a “Passive” wait, reducing CPU usage while maintaining pacing.
Limit	YourHz - 3	Keeps you within the G-Sync/VRR “Safe Zone” ($Hz_{max} – 3$).
Passive	1	Uses the CPU’s sleep state instead of “Busy Waiting” for efficiency.
FrontEdgeSync	1	The Secret Weapon. Times the frame delivery to the start of the refresh.

[Framerate]
; Limit: Set to 141 for 144Hz, 237 for 240Hz
Limit=141
; Mode: 0=Async, 1=FrontEdge, 2=Reflex
LimitMode=2
; Passive: 1 reduces CPU load by ~10% with 0.1ms accuracy trade-off
Passive=1

[RendererDirect3D12]
; High-performance DX12 flags for 2026
QueueLimit=1
WaitableSwapChain=1

HowTo: Engineering the Perfect Frame-Time Graph

Follow these GameEngineer.net technical steps to achieve a perfectly flat line in your performance overlay:

1. The “Minus 3” Rule: For G-Sync/FreeSync to stay active, the GPU must never reach the monitor’s maximum refresh rate. If you have a 165Hz monitor, set your RTSS limit to 162. This ensures you never trip the traditional V-Sync lag penalty ($L_{vsync}$).
2. Toggle Scanline Sync (For Non-VRR): If you are on a fixed 60Hz or 120Hz display without G-Sync, use Scanline Sync. In the RTSS UI, set your limit to 0 and Scanline Sync to a value like -30. This “hides” the screen tearing line in the monitor’s top bezel, giving you V-Sync smoothness with nearly zero lag.
3. Reflex Overwrite: If a game already has “NVIDIA Reflex” in the menu, the RTSS LimitMode=2 will act as a secondary guardrail. It is safer to use the RTSS cap as it is more stable than the engine-level caps found in most Unreal Engine 5 titles.
4. CPU Core Isolation: If you have a high-core-count CPU (Intel 16th Gen / Ryzen 9000), RTSS might trigger a “Busy Wait” on Core 0. Setting Passive=1 in the .cfg allows the CPU to enter a low-power state between frames, which can actually reduce micro-stutters caused by CPU thermal throttling.
5. The “Frametime” Metric: Don’t just look at FPS. In the RTSS overlay, enable the Frametime Graph. A “Perfect” limit is not one that shows “144 FPS,” but one that shows a constant 6.9ms (for 144Hz) or 4.2ms (for 240Hz) with zero vertical spikes.

Technical Explanation: Front-Edge Sync vs. Back-Pressure

Standard frame limiters work by waiting after the frame is rendered ($T_{wait\_post}$). RTSS’s Front-Edge Sync works by calculating the exact moment the monitor starts a new refresh cycle and releasing the “Wait” signal just before that moment ($T_{wait\_pre}$).

Mathematically, this aligns the Frame Present ($P$) with the V-Blank ($V_b$) interval. When $P \approx V_b$, the monitor receives the most recent data possible without the GPU having to sit idle and “waste” potential performance. This minimizes Input-to-Display Latency ($D_L$) by ensuring the “freshest” possible frame is always at the top of the monitor’s scan-out buffer.