How to Set a Fan Curve in the BIOS, Step by Step (Any Brand)

In this guide (9 sections)

• What do you want to fix?
• 1. Know which fan is on which connector
• 2. Open the fan settings in your BIOS
• 3. Set the fan mode
• 4. Draw the curve
• 5. Choose which temperature each fan follows
• 6. Make the fan speed ignore short spikes
• 7. Save and test
• Real cases: what other users ran into

A fan curveFan curve: A setting that decides how fast the fans spin at each temperature. More in our Cooling & noise glossary →Close ✕ tells each fan how fast to spin at each temperature. A good one keeps your PC quiet on the desktop and cool in games, and you can set it in the BIOSBIOS (UEFI): The motherboard's built-in settings program, which starts the PC before Windows. You open it with Delete or F2 at startup. More in our Startup & BIOS glossary →Close ✕ without installing anything. The menus look technical, but the steps are the same on every brand, and you can always undo them by loading the defaults.

What do you want to fix?

Your goal	What to change	Where to look
A fan won’t slow down at all.	Check its mode (PWM or DC)	Step 3
You want the PC quieter on the desktop.	Lower the left part of the curve	Step 4
You want the PC cooler in games.	Raise the right part of the curve	Step 4
The case fans react too closely to the processor’s temperature.	Pick another temperature source	Step 5
The fan speed keeps going up and down.	Add a step-up / step-down delay	Step 6

1. Know which fan is on which connector

Every fan plugs into a small socket on the motherboard called a fan connectorFan connector (CPU_FAN, CPU_OPT, AIO_PUMP): The small 4-pin sockets on the motherboard where fans plug in. The motherboard checks the one labeled CPU_FAN at startup. More in our Cooling & noise glossary →Close ✕. In the BIOS, each connector has its own settings, so you need to know which fan is where.

Which fan goes in which connector

Typical labels near the top of the motherboard. Names vary by brand: check the manual.

• CPU_FAN
  The cooler's fan, or the liquid cooler's speed cable. Checked at every startup.
• CPU_OPT
  A second cooler fan.
• AIO_PUMP / W_PUMP
  A liquid cooler's pump. Usually runs at full speed.
• SYS_FAN / CHA_FAN
  Case fans. Never the processor cooler.

Why "CPU Fan Error" appears: at startup the motherboard reads the speed on CPU_FAN. If nothing is plugged in there, or the fan spins too slowly to register, it stops and shows the error to protect the processor.

Note which connectors have 4-pin plugs and which have 3-pin plugs. You’ll need that in step 3.

2. Open the fan settings in your BIOS

Restart the PC and press Delete (or F2) repeatedly as it starts. Then find the fan section. The name depends on the brand, and on newer BIOS versions it may move a little:

• ASUS: in EZ Mode, click QFan Control (often F6). In Advanced Mode (F7), go to Monitor → Q-Fan Configuration.
• MSI: open Hardware Monitor on the main screen.
• Gigabyte: open Smart Fan (often F6).
• ASRock: go to H/W Monitor, where you’ll find FAN-Tastic Tuning.

If your PC is a prebuilt from a big brand, its BIOS may have only basic options. In that case, the maker’s own app or the free tool Fan Control may give you more control in Windows.

3. Set the fan mode

Each connector needs to know how to control its fan, called the fan modePWM and DC fan modes: Two ways the motherboard controls a fan's speed. 4-pin fans use PWM; 3-pin fans need DC mode. More in our Cooling & noise glossary →Close ✕:

• 4-pin fans: PWM.
• 3-pin fans: DC (sometimes “Voltage”).
• Auto usually works, but if a fan won’t slow down, set the mode by hand.

Some motherboards offer an automatic test (ASUS calls it QFan Tuning) that spins each fan up and down to learn its speeds. Run it once after changing fans.

4. Draw the curve

Pick a fan, choose Manual or Custom, and set the points. Here’s a balanced starting point for the processor cooler:

CPU temperature	Fan speed
30–40°C	20–30%
50°C	35%
60°C	50%
70°C	70%
80°C	90%
85°C and above	100%

A balanced CPU fan curve

Example for a typical desktop processor. Across: CPU temperature. Up: fan speed.

• An aggressive curve: loud as soon as the processor warms up.
• Balanced curve: quiet on the desktop, rising steadily, full speed only near 85°C.

Rules that keep you safe:

• Never set the processor cooler to 0% or let it stop: the motherboard may show a CPU fan error and the processor can’t be cooled.
• Keep full speed at or below about 85°C, well before your processor’s limit; see safe CPU temperatures.
• For the case fans, a similar curve works, often a little slower. Many case fans are quiet even at 40–50%.
• A liquid coolerAIO liquid cooler: A sealed liquid cooler for the processor: a pump on the chip, tubes, and a radiator with fans. More in our Cooling & noise glossary →Close ✕’s pump is different: most makers recommend a fixed, high speed. Check its manual before slowing it down.

5. Choose which temperature each fan follows

By default, most fans follow the processor temperature. That’s right for the processor cooler, but it makes case fans react to every short spike.

Better choices, if your BIOS offers them:

• Case fans: a motherboard or “system” sensor, or the graphics card temperature on some motherboards, which changes more slowly.
• Liquid cooler radiator fans: the liquid (coolant) temperature, if the cooler reports it. It rises and falls smoothly.

6. Make the fan speed ignore short spikes

Processors jump by 10–20°C for a second whenever you open an app. Without a delay, the fan speed follows every jump and keeps changing.

Fix: look for a step-up / step-down timeFan step-up / step-down time: A BIOS setting that makes fans change speed gradually, so short temperature spikes don't make them roar. More in our Cooling & noise glossary →Close ✕. MSI calls it Fan Step Up / Step Down; other brands call it smoothing, response time or spin-up delay. A few seconds is enough. If your motherboard has no such option, a flatter curve at the bottom (for example 30% from 30°C all the way to 55°C) has a similar effect.

7. Save and test

1. Press F10 to save and restart.
2. On the desktop, listen: it should be quieter.
3. Play a demanding game for 15–20 minutes with HWiNFO open, and check the processor stays in a healthy range.
4. Too hot? Raise the right part of the curve. Still loud on the desktop? Lower the left part.

If anything goes wrong, enter the BIOS and load the default settings (often F5 or “Load Optimized Defaults”).

Real cases: what other users ran into

These are real reports from PC forums, summarized in our own words, with a link to each original thread. They show where BIOS fan control reaches its limits.

Real caseRyzen 7 5800X · MSI MAG X570 Tomahawk WiFi · Corsair H100iNot solved by the userFans revving at idle, and the BIOS couldn't see themRead what happened

The processor fans kept ramping up at startup and at idle, with the processor around 50–60°C. A member suggested a flatter BIOS curve, but the BIOS didn’t show the cooler’s fans: on this Corsair liquid cooler they run behind the pump, so the motherboard could only read the pump. Replies suggested controlling the fans with Corsair’s software, or plugging them straight into motherboard connectors, and noted that the liquid temperature is a smoother thing to follow. The owner was still frustrated at the end of the thread.

Takeaway: some liquid coolers control their own fans. Use the cooler’s software, or connect the fans to the motherboard. See step 5.

Source: TechPowerUp Forums

Real caseRyzen 5 3600 · ASRock B450 Steel LegendNot solved by the userFan speed chasing every temperature spike, with no delay optionRead what happened

The fan speed went up every time the processor temperature spiked. The owner had partly reduced the noise with ASRock’s FAN-Tastic settings, but couldn’t find a step-up or step-down delay in the BIOS. Other users said some brands offer it and hoped ASRock would add it in a later BIOS, but no fix appeared in the thread.

Takeaway: not every BIOS has a delay setting. A flatter curve at low temperatures, or a fan tool in Windows, can do the same job. See step 6.

Source: ASRock Forum

Real caseASUS ROG Zenith II Extreme AlphaNot solved by the userA BIOS that wouldn't let fans go slow enoughRead what happened

The owner moved the motherboard into a rack-mount case with very fast fans and found the BIOS enforced minimum fan speeds (18–26% depending on the connector). On the connector they used, the fans still spun at about 1,850 RPM. Replies suggested a different motherboard, or fans that run slower at those minimum settings, and re-running the fan tuning after every BIOS update. The thread doesn’t show a way around the minimums.

Takeaway: if a fan is still loud at the lowest setting, the fan itself may be the problem: slower, larger fans are quieter. See step 4.

Source: Level1Techs Forum

Frequently asked questions

Is it safe to change fan curves in the BIOS?

Yes, as long as the processor cooler never stops and reaches full speed before the processor gets near its limit. You can always load the BIOS defaults to undo everything.

Should case fans follow the CPU or GPU temperature?

In a gaming PC, the graphics card often makes more heat than the processor. If your motherboard lets case fans follow the graphics card or a system sensor, that usually gives smoother, more useful behavior.

What’s the difference between PWM and DC fans?

4-pin PWM fans are slowed down with a control signal; 3-pin DC fans by lowering their voltage. PWM fans can usually run slower and more precisely.

Why did my fan settings reset?

BIOS updates and CMOS resets restore the default settings. Write down your curve, or take a photo of the screen, so you can set it again quickly.

Is BIOS fan control better than software?

BIOS settings work without any program running and can’t be changed by an app by mistake. Software like Fan Control offers more options, such as following the graphics card temperature. Use one or the other, not both.

Can I control the graphics card’s fans from the BIOS?

No. The BIOS controls the fans plugged into the motherboard. The graphics card’s own cooling fans are set by the card itself, or by an app such as MSI Afterburner: see how to control GPU fan speed.