This GPU stress test loads your graphics card with an original ray-marched 3D scene: a field of glowing pillars with soft shadows, reflections and several samples per pixel. The load ramps up in steps until the card is fully busy, then holds there so you can watch frames per second, frame times and throttling as the card heats up. Every 5 seconds the test also redraws a fixed check frame and compares it with the first one, which catches the drawing errors that show up as artifacts in games. It works as a GPU test for NVIDIA GeForce, AMD Radeon, Intel Arc and built-in graphics, and for Apple silicon Macs, and it runs online in Chrome, Edge, Firefox and Safari with nothing to install.
How to run a GPU stress test
- Plug a laptop into its charger and close games and video apps.
- Open a sensor app to watch temperatures: GPU-Z or HWiNFO on Windows, or the GPU section of the Task Manager Performance tab.
- Check the graphics name above the scene. It should be the card you want to test (see below if it is not).
- Leave Load on Auto and Resolution on 100%, choose a run time and press Start GPU stress test.
- Watch the scene for specks, stripes, flickering or black frames, and watch the Speed change readout.
- Press Full screen for the heaviest test at your screen's full size. Press Esc to leave full screen and Stop to end the test.
- Press Copy results to save the numbers. Each finished run is also listed under Your recent runs.
What the results mean
| Readout | What it tells you | Normal result |
|---|---|---|
| Frames per second | Frames drawn in the last second | Below your refresh rate, so the card is fully busy |
| Frame time | Milliseconds to draw one frame (16.7 ms is 60 FPS) | Even bars, without tall spikes |
| 1% low | The frame rate of the slowest 1% of frames | At least two thirds of the average |
| Speed change | The last 15 seconds against seconds 5 to 20 of the hold | Within 5%, laptops often 5 to 15% lower |
| Drawing errors | Check frames that did not match the first one | Always 0 |
A driver reset ends the test with a failed verdict, because the browser loses the 3D scene when the graphics driver stops responding. In a game, the same fault shows up as a crash to the desktop or a black screen.
How to compare your results
The frame rate depends on the load, the resolution, the browser and the screen size, so compare runs with the same settings on the same computer. The run history keeps the graphics name, load, render size, average FPS, 1% low and speed change for your last 8 runs, which makes it easy to check a new driver, a cleaned cooler or a different power mode. A separate graphics card should hold the Heavy load at 100% far above the frame rate of graphics built into a processor. If yours does not, check that the test is running on the right graphics.
The screen shows artifacts or the check frames differ
Colored specks, checkered blocks, stripes or flickering polygons, or any count in Drawing errors, mean the card returned wrong results. In order of likelihood:
- An overclock that is not stable. Reset the core and memory clocks to default in MSI Afterburner, AMD Adrenalin or NVIDIA's app, and test again. Video memory overclocks cause most artifacts.
- Heat. If errors start only after a few minutes, the core or the memory chips are overheating. Clean the heatsink and fans and check the case airflow.
- A driver problem. Install the latest driver from NVIDIA, AMD or Intel, choosing a clean installation.
- Failing video memory. Artifacts at default clocks and normal temperatures on an older card point to hardware. Contact the maker if the card is under warranty.
The driver crashes or the screen goes black
On Windows, a driver crash looks like a black screen for a few seconds and the message that the display driver stopped responding and has recovered.
- Power. A desktop that crashes or restarts as the load ramps up may have a power supply that cannot handle the card's short power spikes. Use the separate power cables your card needs, not one cable split in two.
- Unstable settings. Undo overclocks and undervolts, including factory overclock modes in the card's own app.
- Driver. Update the driver. If crashes started after an update, roll it back in Device Manager.
- Heat. Check the fans spin up under load. A fan that stays still at 80 °C needs replacing.
The frame rate drops as the test runs
A falling Speed change with no errors means the graphics card is slowing itself down to stay within a temperature or power limit.
- Laptop power mode. On Windows 11, set Power mode to Best performance under Settings, then System, then Power & battery. Many gaming laptops also have a performance mode in their own app.
- Dust and old thermal paste. A drop that grows through the run points to heat. Clean the fans and vents, and on older cards replace the thermal paste or pads.
- Airflow. Keep a laptop on a hard surface. In a desktop, check that the case fans pull cool air in at the front.
Our guide to laptop overheating covers the cooling fixes step by step.
The test runs on the wrong graphics
The line above the scene shows which graphics the browser is using.
- Laptops with two graphics chips run the browser on the built-in chip to save power. On Windows 11, open Settings, then System, then Display, then Graphics, choose your browser, set it to High performance and restart the browser. On NVIDIA laptops you can also choose the High-performance NVIDIA processor in the NVIDIA Control Panel under Manage 3D settings.
- Desktops use the built-in graphics if the monitor cable is plugged into the motherboard. Plug it into the ports on the graphics card instead.
- Software rendering means the browser is not using the graphics card at all. The webgl test shows why and how to fix it in each browser.
The scene is drawn with WebGL 2. To check the newer WebGPU instead, the webgpu test runs a compute benchmark that measures floating point speed and memory bandwidth.
What a browser GPU test cannot do
A browser cannot read temperature, clock speed, fan speed, power draw or video memory use, and it cannot run the card past the limits the browser sets on a single page. It is a fast check with nothing to install. For a full test, use these tools, all free or with a free edition:
| Tool | Use it for |
|---|---|
| GPU-Z or HWiNFO | Temperatures, clocks, power and the reason the card is limiting its speed |
| FurMark 2 | Maximum heat and power draw, for checking cooling and the power supply |
| 3DMark | Repeatable benchmark scores. Its looped stress tests need the paid edition |
| OCCT | Stress tests with error detection and a video memory test |
| Unigine Superposition | Game-like benchmark runs. Its looped stress test needs the paid edition |
If the scene draws but the frame rate looks wrong on your monitor, the refresh rate test checks the screen side, and the fps test shows how motion looks at different frame rates. To load the processor at the same time, run the cpu stress test in a second window.
GPU stress test questions
Is it safe to stress test a GPU?
Yes, for a card in working order. Graphics cards lower their clock speed as they near their temperature or power limit, and the driver resets if the card stops responding. A stress test only brings out problems that would also appear in a demanding game, at a time when you are watching for them.
How long should I run a GPU stress test?
Five minutes is enough to see the card reach its working temperature and to spot throttling. After changing an overclock, a cooler or thermal pads, run 15 minutes or more, then confirm with a few hours of the games that crashed.
What GPU temperature is normal during a stress test?
Most desktop graphics cards settle between 65 and 85 °C under full load, and the hot spot sensor reads higher. Laptop graphics often run in the high 80s. A browser cannot read the sensor, so keep GPU-Z, HWiNFO or the Windows Task Manager open, and check the limits in the gpu temperature while gaming guide.
Why does my FPS stay at 60 or 144?
Browsers draw at most one frame per screen refresh, so a frame rate stuck at your refresh rate means the graphics card has time to spare. Choose a heavier load or a higher resolution until the frame rate drops below the refresh rate. The Auto setting does this for you.
Why does the test show Intel or AMD graphics instead of my NVIDIA card?
Your laptop is running the browser on the graphics built into the processor to save power. On Windows 11, open Settings, then System, then Display, then Graphics, select your browser and set it to High performance, then restart the browser.
Is this a GPU benchmark?
It gives a repeatable frame rate for the same load and resolution, which is good for comparing your own runs before and after a change. It is not a ranking of graphics cards: browsers, drivers and screen sizes change the numbers too much for fair comparisons between computers.