1 fan on my dual tower cooler is barely moving.

Capalot tom · 22 Jun 2025 at 15:00

Hi all i recently bought a new pc and got a peerless assasin 120 SE cooler, everything been fine for around 3 weeks but now im noticing 1 fan on the dual tower cooler is barely moving while the other is at full speed. Is this something to be worried about or is it normal? Thanks.

Kelt · 22 Jun 2025 at 15:07

Doesn't sound normal to me, I'd be investigating.

Rob_B · 22 Jun 2025 at 15:08

Are they on different fan headers? If so then you'll need to change the fan curve on the slow one to match.
If they're daisy chained and on the same header then have you checked there is nothing obstructing it?

Hotwired · 22 Jun 2025 at 15:08

Check it's actually powered.

A not working fan sandwiched with a working fan will spin just from the airflow of the other.

Capalot tom · 22 Jun 2025 at 15:14

Rob_B said:
Are they on different fan headers? If so then you'll need to change the fan curve on the slow one to match.
If they're daisy chained and on the same header then have you checked there is nothing obstructing it?

I didnt build it so im not sure. The fan seems to be spinning at full speed now after about 20 mins after booting. Is there a way to check the speed as im just going off looking at it, not clued up in the slightest when it comes to this.

Kelt · 22 Jun 2025 at 15:18

Capalot tom said:
I didnt build it so im not sure. The fan seems to be spinning at full speed now after about 20 mins after booting. Is there a way to check the speed as im just going off looking at it, not clued up in the slightest when it comes to this.

I use HWINFO64.

HWiNFO Download v8.26

Download HWiNFO64 to gain in-depth insights into your PC's hardware. This diagnostic tool provides detailed information about your operating system, storage, RAM, CPU details, memory speeds, and thermal data. Ideal for monitoring system health and performance.

www.guru3d.com

Capalot tom · 22 Jun 2025 at 15:34

Kelt said:
I use HWINFO64.

Not sure if im looking at the right thing but on the sensor tab i go to the motherbaord section and it says CPU is running at 1200 RPM and system 4 at 1100 RPM.

Rob_B · 22 Jun 2025 at 16:31

You really need to see what your fans are plugged into.
You could have both CPU fans in 1 header and case fan(s) in the other, or you could have each CPU fan on a different header and case fans just powered by molex.

If it were me, I'd stop one of the fans on the CPU cooler and see if the RPM goes down in HWInfo, then try the other, then try case fans. This lets you know what's plugged in where.

freddie64 · 22 Jun 2025 at 16:49

What motherboard have you got?

If it only has one CPU fan header they should have used the fan splitter that comes with the cooler so both fans use the same header.

neojay · 22 Jun 2025 at 17:03

Like others have said check where they are plugged in. One fan is prob plugged into a different fan header with different fan profile

pastymuncher · 22 Jun 2025 at 19:04

With Thermalright coolers (and many others I should imagine) you plug one fan into the other (daisy chaining) and then connect that one to a single motherboard header so that the motherboard can control their speed. They should both be doing the same speed but it sounds like either your second fan isn't plugged in properly and is only getting a connection every now and then or it isn't plugged in at all and the fan is just spinning from the airflow from the other fan.