How to Set a Fan Curve in BIOS (ASUS, MSI, Gigabyte, ASRock)

Every PC I build gets its fans set up in the BIOS before I call it done. Out of the box, a lot of boards either run the fans louder than they need to or ramp them up and down every time the CPU blips. A simple fan curve fixes both. This guide is for desktop PCs. Most laptops don’t let you set curves in the BIOS, so for those see laptop fan loud or always running.

Step 1: Headers and fan types

Your motherboard has fan headers labeled things like CPU_FAN, CPU_OPT, SYS_FAN or CHA_FAN, and sometimes AIO_PUMP or W_PUMP.

• CPU_FAN: the CPU cooler fan goes here. The board checks this header at startup. With nothing plugged in, many boards show a CPU Fan Error.
• CPU_OPT: a second cooler fan, or the second fan on a dual-fan cooler.
• SYS_FAN / CHA_FAN: case fans.
• Pump headers: for AIO liquid cooler pumps. These usually run at full speed.

Fan types:

• 4-pin fans are PWM. The board sends a speed signal.
• 3-pin fans are DC (also called Voltage). The board slows them by lowering the voltage.

Gigabyte’s BIOS manual says it plainly: Voltage mode is recommended for a 3-pin fan, and PWM mode for a 4-pin fan. Auto lets the BIOS detect the fan type. A 3-pin fan on a header set to PWM usually just runs at full speed, so if one fan is always loud, check that first.

If you use a splitter or hub, keep all the fans on it the same type, and check that the header can supply enough power for them. A SATA-powered hub takes that load off the header.

Step 2: Find the fan page in your BIOS

Press Del (or F2 on many boards) right after you power on. Each brand puts the fan settings in a different place:

• ASUS: Q-Fan Control, the button at the top of the BIOS, or press F6. ASUS’s BIOS manual says you select a fan, pick a profile or Manual, then drag the speed points and click Apply. PWM and DC mode buttons are on the same screen.
• MSI: Hardware Monitor in Advanced mode. Pick the fan, choose DC or PWM, and drag the duty points on the curve. MSI calls automatic control Smart Fan Mode.
• Gigabyte: Smart Fan 5 or 6, depending on the board. Gigabyte’s manual lists Normal, Silent, Manual (drag the curve nodes, then Apply), and Full Speed. It also lets you choose which temperature the fan follows, and has a Fan Stop option.
• ASRock: look under Advanced or H/W Monitor for the fan configuration. The exact menu depends on the board, so check your manual. In Windows, ASRock’s own A-Tuning utility has FAN-Tastic Tuning, which lets you set up to five temperature points on a graph.

Step 3: Set a simple curve

Start with a preset like Standard, Normal, or Silent. If you want to go manual, here’s a starting point I like for case and CPU fans. Tune it to your build.

• Up to about 40°C: low and quiet, around 30 to 40%.
• 60°C: around 50 to 60%.
• 75°C: around 80%.
• 85°C and up: 100%.

Tips:

• Don’t set the bottom so low that the fan stalls. Some 3-pin fans won’t start below roughly 40% on DC.
• If the fans keep ramping up and down, look for a smoothing, “step up/step down,” or temperature interval setting. Gigabyte calls it Temperature Interval. It slows how fast the fans react.
• Case fans can follow the CPU temperature, or on some boards a motherboard or chipset sensor.
• Leave AIO pumps at full speed unless the cooler maker says otherwise.

Save and exit (often F10), then run a game or benchmark for 10 minutes and watch temperatures in a monitoring tool. They should level off, not keep climbing.

Step 4: Fix a “CPU Fan Error” at boot

ASUS’s support page lists these fixes:

• Make sure the cooler’s fan cable is plugged into CPU_FAN, not a CHA_FAN header.
• If you’re using a slow-spinning fan, lower the “CPU Fan Speed Low Limit” (ASUS suggests 200 RPM).
• On an AIO liquid cooler where nothing is on CPU_FAN, you can set the CPU fan speed check to Ignore. Only do that if the pump or radiator fans are being monitored somewhere else.
• Update the BIOS.

Prefer to control fans from Windows?

The free Fan Control app (by Rem0o) can set curves for motherboard fans and many graphics card fans from Windows, using any temperature sensor. It’s built for desktops. It still relies on the BIOS for the PWM or DC setting, so set that first. Brand apps like ASUS Armoury Crate, MSI Center, Gigabyte Control Center, and ASRock’s utilities can do this too.

If a fan stays loud no matter what

• Dust: see clean a dusty desktop.
• CPU running hot: old or bad paste. See thermal paste and pads.
• Clicking or grinding: a cable in the blades or a worn bearing. The checks in laptop fan not spinning and replace a laptop fan apply to desktop fans too.
• Graphics card fan: it’s controlled by the card, not the BIOS. Use the card maker’s app or Fan Control. If the card itself acts up, see reseat a GPU.
• Power supply fan: don’t open the power supply. See PSU, not the motherboard.

When you’re working inside the case, follow anti-static habits that matter.