Some tower CPU coolers use two fans. The front one that pushes air into the fin stack and a rear fan that pulls it through. This push–pull setup improves the efficiency of heat removal from the heatsink and can lower temperatures by a few degrees. You’ll find the same idea in the new generation of graphics cards from Asus and Gigabyte. Here, we look at how a fourth fan affects noise levels and temperatures on the Aorus GeForce RTX 5080 Master 16G.
The fourth fan on the cooler is another source of noise. The add-on fan bundled with the card is a different size and design, so you shouldn’t expect it to run at the exact same RPMs or produce the same noise at a given speed. It also has a different operating RPM range from the three stock fans, and it isn’t controlled by the card—it has to be driven externally. For the test, we connected it to a Corsair Commander Pro controller.
First, let’s look at how it affects the card’s noise level. I plotted the measured noise values into a 3D graph. This is for the Performance BIOS, which has a slightly higher minimum speed—the lower limit is 1100 RPM.
The left edge of the surface represents the card’s noise level with the supplemental fan stopped. The front corner corresponds to 1100 RPM for the trio of “Hawk” fans and 0 RPM for the add-on fan. Moving left from this corner, the card’s fan speed increases up to approximately 3000 RPM.
Along the other horizontal axis are the speeds of the fourth fan mounted on top of the card; I set these between 800 and 1670 RPM. The vertical axis shows the resulting noise level. When tuning fan control, you’ll want to find a balance where the fourth fan isn’t louder than the three on the cooler—and vice versa. That way, you get higher airflow through the fin stack at a similar overall noise level.
The graphs below show the measured operating characteristics. These are measurements across the entire speed range in both directions of the graph.
The values were measured by first setting the speed of the fourth fan, which remained constant throughout the entire test run. The performance level will be set in steps to the following values:
- 0 %: 0 rpm
- 32 %: 800 rpm
- 43 %: 1000 rpm
- 65 %: 1320 rpm
- 76 %: 1490 rpm
- 98 %: 1760 rpm
For each setting of the fourth fan’s power level, I then ran measurements across the entire operating range of the trio of fans on the card. For temperature measurements, I switched to the Silent BIOS, which has a lower minimum speed limit at 30% and 1000 RPM. The measurement starts at 100% fan power (approx. 3000 RPM) and the speeds gradually decrease in 5% steps down to 30% power and 1000 RPM.
Three test runs are executed for each setting. The values are taken from the third segment with the fans at low speeds, where the card was relatively quiet.
On the graph showing temperature progression, the added fan is most noticeable at high speeds at the end of the measurement, where the trio of fans on the card is running at low speeds around 1200–1000 RPM. Then, logically, the fourth fan at 1500 RPM helps to bring the temperatures down. However, this comes at the cost of a significant increase in noise.
If the fan speeds are similar, the benefit of the fourth fan is not very noticeable due to normal temperature fluctuations.
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