How to use the NVIDIA Reflex Latency Analyzer

By Seth Schneider on January 15, 2021 | Featured Stories G-SYNC NVIDIA Reflex

Over the years, NVIDIA has accelerated framerates, minimised micro stuttering, and introduced dozens of enhancements that make gameplay faster and smoother. Now, we’re tackling system latency with NVIDIA Reflex, a revolutionary suite of GPU, G-SYNC display, and software technologies.


End to end system latency (a.k.a. “input lag” or “system lag”) determines the responsiveness of gaming experiences, affecting the time it takes for your clicks to become actions on-screen. Long delays make gameplay feel sluggish, and could well get you killed in competitive multiplayer matches.

The first step to fixing your system latency is measuring it. To enable system latency monitoring, we’ve added NVIDIA Reflex Latency Analyzer hardware into the new G-SYNC monitors. This enables instantaneous latency analysis that is as-accurate as a 1000 FPS camera, without any of the fuss or expense, giving competitive players full confidence in the capabilities and responsiveness of their systems (no longer can they blame the PC when whiffing a clutch moment!).


We’ve also worked with mouse manufacturers to enable real-time latency measurement of mouse clicks, too. When a compatible mouse is plugged in to a specific Reflex Latency Analyzer monitor USB port, real-time data is collected and added to system latency stats, giving users end to end system latency for the very first time.

In this guide, you will learn how to set up your NVIDIA Reflex Latency Analyzer, which mice are compatible, and some tips and tricks when measuring system latency.

How To Setup and Use NVIDIA Reflex Latency Analyzer

If you’re buying or have already bought a Reflex Latency Analyzer-compatible G-SYNC display, here’s how to setup and use the tech. Please note that all monitors differ, so please refer to your monitor’s manual for specifics on UI options and USB port usage.

Hardware Setup

  1. Connect the display port cable -- Set up your new G-SYNC 360Hz display, and using the included DisplayPort cable, connect it to a DisplayPort output on your GeForce GPU.
  2. Connect the provided USB cable -- connect the cable from your monitor to your gaming PC.  This cable should be a USB Type A (Goes to PC) to USB Type B (goes in Monitor)
  3. Connect your gaming mouse to the Reflex Latency Analyzer port -- Refer to your monitor’s documentation for the specific port.  There is typically only one port on the monitor that supports Reflex Latency Analyzer.

Software Setup

4. Turn on Reflex Latency Analyzer -- In the monitor’s On Screen Display (OSD), locate “G-SYNC Processor” and switch “NVIDIA Reflex Latency Analyzer” to ‘On’.  There should now be an overlay on your monitor that shows PC + Display Latency.

Alienware OSD Example

a. Tip: If your mouse is connected to the correct port, there will be an XXX.X that appears in the monitor overlay when you click.

5. Setup the Monitoring Rectangle -- Reflex Latency Analyzer detects flashes, like muzzle flash from a weapon or any bright change on the screen, to end each measurement. Those flashes are detected at a certain region on the screen called the monitoring rectangle. In order to measure latency, move the monitoring rectangle over the location on screen where you expect a flash or a change in brightness to occur when the left mouse button is pressed. To do this, select the monitoring rectangle location in the monitor’s OSD.

Monitoring Rectangle Picture

a. Tip: The “show rectangle” option does not need to be enabled for Reflex Latency Analyzer to detect flashes.

6. Measure PC + Display Latency -- Now that the monitoring rectangle is configured, you should be able to measure PC + Display Latency when the left mouse button is pressed.

7. Setup GeForce Experience Performance Overlay -- Now that we can measure PC + Display latency, let’s get even more stats and full system latency with GeForce Experience.

a. Download the latest GeForce Experience.

b. Open GeForce Experience, click the cog icon on the top right to access the Settings, click General on the left, and tick the “Enable Experimental Features” box.

c. Ensure the GeForce Experience “In Game Overlay” option is enabled.

d. Open GeForce Experience, press Alt+Z to invoke the in game overlay, and click “Performance”

e. Click the cog icon to access the settings for this new screen

f. In the new HUD layout menu, click “Performance”, select a position for statistics to be display, then select “Latency” in the list of five options

g. Various stats will now be displayed, though most will be “0” until we get into a game and start testing. To toggle the overlay, press Alt+R

h. If everything’s working correctly, you will now see a full range of stats in the overlay once testing has started.

i. Note - you do not need to have the Reflex Latency Analyzer enabled in the OSD for the GeForce Experience performance overlay to work. The GeForce Experience performance overlay will enable Reflex Latency Analyzer in the background once the overlay is enabled.

A quick breakdown of the above stats:

  • FPS: Frames per second from the GPU—the measure of throughput—not latency.
  • Render Latency: The time from when the frame gets in line to be rendered to when the GPU completely renders the frame.
  • Reflex Monitoring Position: Monitoring rectangle’s center coordinates.
  • Mouse Latency: Mouse peripheral latency only.
  • PC + Display Latency: Measured from the moment the mouse click is received by the OS to the end of display latency. Monitor OSD reports this.
  • System Latency: The time encompassing the whole end-to-end measurement — from the start of peripheral latency to the end of display latency (requires Reflex Latency Analyzer supported mouse). GeForce Experience reports both PC + Display and total System Latency.
  • Averages: Average results from the past 20 clicks.

Reflex Latency Analyzer-Compatible Monitors and Mice

To help competitive gamers find the right gear for the Reflex Latency Analyzer, our website now features a compatibility section tracking G-SYNC monitors featuring the Reflex Latency Analyzer hardware, and mice that work with the full range of Reflex latency measurement features.

Mouse Compatibility View

Please note that older versions of these mice will require updating to the firmware version listed to work with the Reflex Latency Analyzer. Please check manufacturer websites for new firmware and the latest information about Reflex Latency Analyzer support.

If your mouse isn’t compatible yet, NVIDIA has compiled a repository on GitHub of average mouse latencies for the most popular models. When using the Reflex Latency Analyzer with a mouse in the database, the analyzer will show the average mouse latency to give you a general idea of the latency added by your mouse.

Top 10 Tips and Tricks

Where do I position the Reflex Latency Analyzer monitoring rectangle? How do you find the right spot? We’ve performed thousands of hours of testing—here are our top tips for improving your Reflex Latency Analyzer experience:

  1. Muzzle flashes are usually the best area to measure - In most game worlds, nothing is faster than a bullet. The next fastest element after the bullet is the escape of gases that result in muzzle flash. This is your go-to for quickest luminance change.
  2. But beware of muzzle bloom - Some weapon muzzle flashes can take longer than others to fully bloom, so be sure to place the monitoring rectangle directly in the center of the muzzle flash to avoid capturing the end of the animation.
  3. Keep the monitoring rectangle in the same exact spot - Ensure the monitoring rectangle is placed in the exact same spot for each test. If the rectangle is placed only a bit higher than your previous rectangle location, the muzzle flash animation could be captured at an earlier interval, effectively lowering latency, potentially by 3 ms — 16 ms (depending on the refresh rate of the display).
  4. You can reprogram the left-mouse button to another action - Most of the time, the left mouse button is keyed to an attack, but in case it isn’t, or a better option is available, you can always key another action to the left mouse button. Reflex Latency Analyzer works with the left mouse button as input.
  5. Accurate results require many tests - You’ll see latency variability from test to test, including some outliers that are much longer or shorter than the rest. You’ll want to perform many benchmark tests to minimize the inherent variability. We recommend collecting 100 samples per test if you plan to publish an “average” latency value.
  6. Each game is unique - While Reflex Latency Analyzer is the easiest and most accurate way to measure latency, you will have to tailor the rectangle placement for each game and scenario. This is because each game animates differently and features different weapon behaviors. You will want to experiment to see what works best for each game. The next section explains more in detail. But if you aren’t getting good results, move the rectangle to a different area on the weapon or arm, or decrease the size of the monitoring rectangle, or face the game camera against a different background.
  7. Make testing easier and more accurate with the Flash Indicator - Fortnite supports the latency flash indicator which displays a white box on the left side of your screen when the mouse is clicked. Place the Reflex Latency Analyzer monitoring rectangle inside this box.
  8. You can measure on objects or backgrounds - Try placing the rectangle on a weapon that recoils or attacks away, leaving the rectangle exposed to the background behind the object. You can also try the opposite: placing the rectangle on the area right above a weapon barrel, which then measures the muzzle flash as it jumps into range.
  9. Watch out for sway - Some games feature heavy camera or character sway. Make sure this excessive movement doesn’t interfere with measurements. In these circumstances, experiment with the rectangle placement and take individual measurements while adjusting the target area to find the sweet spot.
  10. Don’t make the reflex monitoring rectangle too large - Stay near the luminance change. A larger rectangle that is greatly beyond the targeted measuring area could fail or result in excess variability.

Game Testing Scenarios

Our team has spent thousands of hours in Reflex-enabled games, and other titles, finding the best way to benchmark and test. Follow the steps below to test Apex Legends, Call of Duty: Warzone, Valorant, and other leading competitive multiplayer games.


Fortnite has its own built in latency flash indicator, allowing players to more consistently measure the responsiveness of their system!

To use this feature, set Latency Flash to On in the Video options. Click the mouse button to make the flash indicator appear (white box) and move the monitoring rectangle to that location. Adjust the monitoring rectangle to fit inside the flash indicator In Display settings, set Framerate Limit to Unlimited.

  1. Change to Creative gameplay mode and click Play.
  2. Move forward towards the yellow rift and use the console.
  3. Select a creative island and click confirm.
  4. Enter the rift when the map is finished loading
  5. Press I on your keyboard to access settings, choose My Island, and enable infinite ammo and infinite resources.
  6. Press I on your keyboard to access settings, choose Creative, and click and hold the orange Assault Rifle and drag it into the equipment slot.
  7. Find an area for testing and stand in the same location for consistency.
  8. Enable Toggle Targeting to remain zoomed in without having to hold right-mouse click. This will also make the muzzle flash larger. Enable the Latency Flash indicator to make testing easier.


  1. Choose Custom Game and click Options to enable Cheats. Change map to Haven.
  2. Click Start to launch the private server.
  3. Once the map loads, press ESC and navigate to Cheats and enable all Game cheats
  4. Find an area for testing.
  5. Use the classic or vandyl for instantaneous muzzle flashes. Beware—some weapons have a slower muzzle animation.

Call of Duty: Warzone

  1. Click Warzone.
  2. Click Practice Modes and Trials.
  3. If you want to test in a Battle Royale map, choose Battle Royale Practice to play with enemy bots, but don’t worry we have provided a technique to avoid them.
  4. Click Play Training.
  5. The cargo plane will fly over the quarry. Look for the tower highlighted below. Once the option is available, press SPACE to exit the plane and aim towards the tower. Press SPACE again to deploy your parachute and land on the tower.
  6. Land in the designated area.

7. After landing, position yourself directly up against the metal beams and hold W to carefully slide to the right so that the other parts of the metal tower are no longer visible. Place your crosshair in the middle of the beam so that the mountain/trees and buildings remain visible. Ensure that you are facing the Southeast.

8. Place the Reflex Latency Analyzer monitoring rectangle on your crosshair. Press 2 to switch to the pistol and shoot.

Apex Legends

Apex Legends has an FPS cap (144). To remove the FPS cap, follow the steps below.

  1. Choose Firing Range
  2. Find and equip the Spitfire machine gun
  3. Place the Reflex Latency Analyzer monitoring rectangle on the carrying handle of the Spitfire
  4. Stand in the area pictured below and fire the gun. We chose to place the monitoring rectangle on the carrying handle of the Spitfire (marked with a red box) because the pixels on the carrying handle light up first before the muzzle flash appears. This also makes it easier to test since luminance changes are detected from dark to light (map is very bright).

CounterStrike: Global Offensive (CS:GO)

  1. From the main game menu click the gear and set Enable Developer Console (~) to Yes.
  2. Click the Play CSGO button. From the drop down menu click Practice with Bots. Underneath the drop down choose Competitive and select the No Bots option to the right, then pick Inferno as the test map and click Go.
  3. Input these other commands into the developer console when the map loads:
  • sv_cheats 1
  • mp_roundtime_defuse 60
  • mp_buy_anywhere 1
  • mp_restartgame 1 – Choose the Terrorist side (or Press M)
  • sv_infinite_ammo 1
  • give weapon_awp

4. With the AWP equipped, zoom in once with right-click

5. Position the Reflex monitoring rectangle on the darkened area outside the sight.

Other Games

Following these steps, you can see clear patterns about how to best measure latency. Using these as a template, you can readily identify test locations in other titles, helping you measure system latency in virtually any game.

Reflex Latency Analyzer: Available Now In G-SYNC 360Hz Esports Displays

For the first time ever, gamers can accurately discern their end to end system latency, helping them modify their systems and game settings for a superior, more competitive experience. Check out our in-depth latency optimization guide that will help you get started and optimize your system for the lowest latency.

Grab a G-SYNC 360Hz Esports Display today to start testing for yourself!