Question Think I have an Uncontrollable Fan

Oasis Curator

Apr 9, 2019
I have an MSI MPG B560i Gaming Edge motherboard.
Connected the CPU fan and it's pretty good.
Connected the rear exhaust fan and it's good too.
Both of these are 4-pin

However, I've connected a large front fan, which is 3 pin. I can't remember if the motherboard is 4-pin or 3-pin or if the fan is 4-pin or 3-pin or both are 3-pin but I know both aren't 4-pin.

This means I can't control the speed using BIOS (I don't think) or the MSI software (tried, but changing the speed does nothing).

I think the fan is running at full RPM (about 1100?).

As it's a simple HTPC for playing movies only (although is fully fledged Windows), I don't need it to be so fast and loud.

Is the only option to use one of the little adaptors (luckily my CPU fan - noctua - came with one) to reduce the speed hardware wise?

EDIT: I think the motherboard has 4-pins but the case fan - a 140mm one - only has the 3 pins, hence not being able to control it.
Case is a Fractal Design Node 304, but I have a Silent Wings 3 fan and the case takes 120mm so should be good to swap, which means I'd be able to control the speed.

EDIT 2: So my front intake fan (92mm) is plugged into the SYS_FAN1 plug on the motherboard.
My CPU is plugged into the CPU one.
I've plugged the rear fan (was 3-pin, now 4-pin) into the PUMP_FAN plug on the motherboard as there isn't any other socket.

Manual excerpt:

I've read (on reddit) the motherboard will automatically run "pump fan" fans at 100% because it's for water cooling. I haven't tried adjusting the speed of the new 4-pin fan to see if it will adjust as it's late but wanted to get this down for prosperity / comments.

I also need to check in the BIOS that the PWM is set to on for those fans.
If the front intake fan (SYS_FAN1) is running at 100% (I think according to the manual, it should), then it's pretty quiet. Is that because it's not getting much power (1A 12W)?
Last edited:


From BIOS, set those fans that are 4-pin, to PWM mode. And that fan which is 3-pin, into DC mode. This enables control of all of them.

You can also control 4-pin fans in DC mode. But if you have 3-pin fan running in PWM mode, then fan runs 100% without you being able to control it's speed.

Is that because it's not getting much power (1A 12W)?

This is not a thing.

1A @ 12V is max what MoBo fan header can provide. While 92mm fan needs ~ 0.2A @ 12V to run at 100%. This metric (1A @ 12V) is there to let you know how many fans you can connect to single header. E.g if fan is rated for 0.2A, then you can connect 4x such fans into single header. If fan is rated for 0.3A, then two fans per header. Connecting more, very close to the max what MoBo header can provide, isn't advised since fans have start up power spikes, that can surpass their Amperage rating, thus frying the MoBo fan header (for they very least, or frying entire MoBo at worst).
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