Fan Control Basics

Open Cooling in the sidebar. The page is your fan list on the left and your curves on the right, with the preset tabs across the top of both.

1. The page

The left column is the Fans rail: one card per fan or pump channel, with an editable name, live RPM, a duty bar, and a mode dropdown. Fans from external hubs and coolers are grouped under their device; motherboard fans list on their own. You can rename fans, drag cards to reorder them, and collapse device groups. Its header carries the channel count, the Calibrate button, and Select all / Select none.

The right column is Curves: a block of curve buttons over the Curve Editor for whichever curve is open. The badge beside the title says what pressing a curve would apply to - the fans you have selected in the rail, or nothing.

The chip at the left of the tabs opens the page's own menu, holding Off and the switch between Simple mode and Advanced mode. Simple mode is three large tiles - Silent, Balanced, Turbo - and nothing else; curves, per-fan control, saved presets, and calibration are all advanced mode, which is what the rest of this guide describes. At the right of the tab row sits the Presets picker, which saves and restores your whole cooling setup, with undo and redo beside it and an Import... entry when Nexus finds a configuration it can read from another fan tool.

2. Presets

The tabs across the top switch the whole system between cooling presets: All Silent, All Balanced, All Turbo, and Custom, with Off in the chip's menu.

  • Off hands everything back to your motherboard: the page shows "All fans controlled by BIOS". Changing any fan setting other than back to BIOS control automatically moves you to Custom.
  • Silent, Balanced, and Turbo each drive every fan from a built-in preset curve. The preset curves are editable and can be restored with Reset.
  • Custom is your own mix of per-fan modes and curves.

3. Per-fan modes

Each fan card's dropdown sets what drives that fan:

  • BIOS control - Nexus releases the fan; your motherboard (or the hub's passthrough) controls it. This is the hands-off mode.
  • Manual - a fixed duty you set by dragging the fan's duty bar. Manual speeds are saved and restored, including after a restart or when a hub reconnects.
  • A curve by name - the fan follows that temperature curve. See Building a Fan Curve.
  • New curve - creates a curve and binds this fan to it in one step.
  • Firmware control - on hubs and coolers that have their own onboard behavior, hands control to the device's firmware.

There is a second way to bind, and it is faster for several fans at once: select the fans in the rail, then press a curve on the right. Click a card to select it, Cmd or Ctrl click to add more.

On an external hub the cooling mode is a device-level setting, so picking BIOS or Firmware control on one fan switches the whole hub; picking Manual or a curve switches the hub back to software control so Nexus can drive it. Some devices report a channel without accepting control at all: a fixed-speed fan shows a Fixed speed marker, and some pump channels are telemetry only.

Each card's menu holds the rest: Lock, which keeps that fan on its own setting when you switch cooling modes, Turn off Nexus Control to release the channel entirely, Mark fan device to tag a fan as the CPU or GPU fan, and Select only to narrow the selection to it. With several fans selected, those entries act on the whole selection and say how many fans they will touch.

4. Calibration

The Calibrate button in the Fans header sweeps every controllable fan through its full range: "Every fan is driven from 100% down to 0% duty so Nexus can measure its speed range. This takes about 40 seconds." Fan controls are locked while it runs. Calibration measures each fan's real RPM range, and flags fans that ignore duty changes (Fixed speed) or do not respond at all (shown as Disconnected and grouped separately).

5. Safety behavior

  • The curve engine evaluates about once per second, and every duty write is clamped to 0-100%.
  • Speed changes ramp at the rate set by each curve's Response time, instead of jumping instantly.
  • Nexus only ever drives a fan you have put into Manual or curve mode; everything else stays with your motherboard or the device firmware.
  • When the service shuts down, all fans are released back to BIOS control so nothing stays pinned at a low speed. The shutdown dialog states it plainly: "Hardware control returns to BIOS defaults."

Warning

Two programs should not control the same fans at the same time; they will fight and speeds will snap back and forth. Let one app own each device - see Other RGB & Fan Software.

If fans do not respond to what you set, see Fans & Curves.