How to Configure PWM Fan Curves for a 240mm Radiator

Most people leave fan curves on whatever default the motherboard picked and never touch them again, then wonder why their build sounds like a hair dryer during a loading screen. Getting fan behaviour right on a 240mm liquid cooler takes a few minutes in BIOS and makes a bigger difference to everyday noise than almost any other setting.

Quick Answer

Configuring PWM fan curves means mapping fan speed to CPU temperature in your motherboard's BIOS or its bundled software. On the MasterLiquid 240 Atmos, at R1,399, a gentler curve keeps the SickleFlow Edge fans quiet at idle and low load, only ramping up once gaming actually pushes temperatures higher.

🌡️ Understanding what a fan curve actually controls

A fan curve is simply a set of points that tell the fan what speed to run at for a given temperature. Most BIOS interfaces show this as a graph, with temperature along one axis and fan speed as a percentage along the other. Steeper curves ramp fans up quickly as temperatures rise, while flatter curves keep fans slower for longer, trading a bit of extra heat for quieter running.

For a 240mm radiator with two fans, the default curve set by most motherboards tends to be more aggressive than necessary, since manufacturers set defaults conservatively to cover a wide range of CPUs, not just yours specifically.

Finding the fan curve settings

Most modern boards put this under a Q-Fan, Smart Fan or similarly named section in BIOS, usually accessible from the same page as CPU fan header settings. The Atmos connects its fans through standard PWM headers, so they show up like any other case or CPU fan in that same menu.

Picking the temperature source the curve reacts to

Many BIOS menus also let you choose which sensor drives the curve, typically CPU package temperature, a core-average reading, or occasionally a motherboard VRM sensor offered as an alternative. Package temperature reacts fastest to sudden load, which makes it the safer default for a gaming-focused curve, since a slower averaged reading only catches up to a spike after the fans should already have responded.

🎮 Setting a curve for quiet gaming

For gaming specifically, the goal is usually a curve that stays low and quiet through idle and light load, since browsing, chatting or menu screens do not need the fans working hard. A reasonable starting point is keeping fan speed under 40 percent until temperatures climb into the 60s, then ramping more steeply from there so the fans respond quickly once a game actually loads a demanding scene.

Testing the curve during an actual gaming session, rather than just idle desktop use, gives a much better sense of whether it strikes the right balance. A curve that seems fine sitting at the desktop can still feel too aggressive once a demanding title pushes the CPU for an hour straight.

Separating pump speed from fan speed

Where the BIOS allows it, keep the pump running at a steady, higher speed rather than tying it to the same curve as the fans. The pump moving coolant efficiently matters more for consistent temperatures than fan speed does, and pumps are generally quieter than fans at higher speeds anyway.

🎬 Adjusting for streaming or heavier workloads

Streaming and encoding workloads push CPUs differently to gaming, often running sustained high utilisation on multiple cores rather than the bursty single-core spikes typical of most games. For that kind of load, a slightly steeper curve makes sense, since sustained heat needs consistent airflow rather than the burst response tuned for gaming alone.

If you regularly switch between gaming and streaming or rendering, some motherboard software allows saving multiple fan profiles that can be switched between, which avoids constantly re-tuning the curve for each use case.

Full specifications for the fans and radiator on the MasterLiquid Atmos listing are available directly on the product page, and the CPU liquid cooler selection shows other 240mm units if a comparison is useful before finalising your setup. For a broader look at cooling hardware generally, Evetech's complete cooler range lists both liquid and air options together.

Frequently Asked Questions

Where do I find fan curve settings in BIOS?

Most boards place this under a Q-Fan, Smart Fan or similarly named menu, usually alongside other fan header settings.

Should pump speed follow the same curve as the fans?

Not ideally. Keeping the pump at a steady, higher speed while adjusting only the fan curve usually gives more consistent cooling with less noise variation.

What fan speed is reasonable at idle?

Under 40 percent is a common target for idle and light desktop use, ramping up only once temperatures rise during heavier tasks.

Do streaming workloads need a different fan curve to gaming?

Often yes, since sustained multi-core loads from streaming or encoding benefit from a steeper curve than the bursty single-core spikes typical of gaming.

Can I save multiple fan profiles for different tasks?

Many motherboards support this through their bundled software, letting you switch between a quiet gaming profile and a more aggressive one for heavier workloads.