New fan or not? (2018), Noctua vs Stock fan


I received my MK2 Extended Cetus 3D last week and I have had some great prints from it.

I have seen that some complain over the noise from the fan (at the extruder) and some have swap out the stock fan for a Noctua NF-A6x25 (5v) with an 3D-printed adapter to make it fit.

I have two questions you might can help me with:

  1. My stock fan model number is: NMB 04010SS-05L-AA. In this website:

they write that the noise from it is 21 dB.

According to this site about the Noctua:

the noise from the Noctua is 19,3 dB.

That would not be noticeable. Am I missing something or do you have other fans that are louder (earlier model of 3D printer from Cetus maybe)?

  1. The Noctua has a much better airflow and CFM than the stock fan. (see above links again)

Stock fan: 0,14 m3/min = 8,4 m3/h = 4,9 CFM

Noctua fan: 0,486m3/min = 29,2 m3/h = 17,2 CFM

Is this an advantage for the Noctua or not? What can I win with this higher CFM? Shall I replace the stock fan because of this?
I mean shouldn’t the 3D-printer already be design so it is optimized? I don’t want to end up with less quality prints.

Please help me straight out these question marks.

// Tommy


for my opinion it makes only sense if you stick with PLA. Since I started to print ABS and Polycarbonate it is a no-go to cool the nozzle tip itself. Also cool air on the printed part have to be avoided. I only give ariflow to the part of the nozzle where the filament is guided in (just below the feeder).

Yes, the stock fan makes a lot of noise but when you don´t use the air duct the noise level decreases a lot.


Hi Kirkdis33

Thanks for your feedback.

Can I ask how you control the airflow to not hit the nozzle or the printed part?
What kind of air duct do you use?

Another question regarding ABS, as you seems to know more about ABS than me.
I have the heated build plate, would I use it all the time? Or only with PLA, ABS, small or large prints? Is it some rules or guidelines to follow there?


I want to make sure in the point of view connected to this. So if you are looking for the answer, I will be grateful for them here.

Nothing bothers you. You are completely satisfied with how your printer works.
My brother gave me a MK2 Extended Cetus 3D six months ago and I’m happy with everything. I do not understand people who are starting to change the fan.

CUI makes more silent 40x40x10 fans at 15.6 dB with 5.4 CFM, another model is 20.6 dB with 7 CFM. The current fan has been working pretty with PLA filaments. I do not print ABS on my Mk3 because it’s inside my computer room. But I do print PETG at 80C bed temperature and the version 2 of the fan duct (one with a deflector) with great success.

exactly, haters gonna hate. Maybe those people do have noisy fans but all my Cetuses are quiet, not dead silent which some people seem to expect stupidly. if its really noisy record it and send to cetus for advice dont follow idiots saying to put on a quieter fan that doesnt have the flow and response characteristics the printer is expecting. write Noctua on some masking tape and stick it on if that makes you feel better. Personally i do think they could be using better quality fans and other parts and develope to those, but replacing for no reason is idiotic.

All the MK3’s fan are silent now, you can just buy the fan from our online shop. Its is cheaper than Noctua.