You just let the wire hang free over the board?
I assume so, I don’t have the fan but usually they have small sensor ( thermistor ) at the end of the cable.
Hm, to me it looks just like a third wire, out of the box it’s attached to the XH plug so I was thinking it was just for reading out the speed ?!
I’ll give the company a call tomorrow.
Hi again, if it was initially connected to the connected, then definitively is the speed signal. As said, I do not own the fan but int he specs sheet says is temperature-controlled and a lot of this kind of fans have the sensor in a small cable to locate it appropriately. But also says it has an optional speed signal, so I assume that is it.
Then you can leave it disconnected as the PSU does not use it.
Response by seller is:
- third wire is just speed signal
- thermistor should be a 5-10 mm wire at the center of the radiator hub. Honestly I can’t find any wire there…
@FlyByWire, Thaks a lot for the tip, I missed it 
Here should be the update:
Alternative PSU Fan 1 (~17 CFM, ~28 dBA)
Alternative PSU Fan 2 (~11-21 CFM, ~15-32 dBA, temperature controlled - thanks to @gpt1plon & @FlyByWire for the right link )
REMARK : The actual PSU cooling fan is quite good and not noisy, the alternatives are similar or slightly worse in CFM besides that to change it you have to dismantle the whole PSU. I would not recommend changing it.
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Sorry I am getting a bit confused by the thread and talking about third wires etc.
Thats the PSU case inner fan?
PSU Case Fan is the one on the back making most of the noise?
@DeltaT, the more noisy one is the PSU case fan indeed, 35mmx10mm, and it requires to change the polarity of the cable as @brent113 showed.
Can’t see his post in this thread?
Yes, I already clarified upper. Unfortunately , cannot correct upstairs
Anyone have any luck finding new hot-end cooling fan alternatives?
The ones linked above are completely different than what they probably were.
Opened PSU and found 25x25x10 and 60x60x10 fans
Going to replace with 40x40x10 and 60x60x15 by EBM-Papst
From 35 en 30dB to 16 and 22 dB with more CFM
unplugged the 25x25 for now (see https://youtu.be/nQoWT_Vo8YY)
PSU did not get over 33C while 3D printing the new backplate for 40x40 here:
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make that over 70dB-A for the smallest one
Has anyone found any of these lower db fans in North America? Shipping from China takes over a month.
I have not replaced any of these, for breakage, but past experience with fans is that it will be easier (in time/aggravation) buying a whole fan than parts for a fan. Getting them working properly again after a repair is… Not worth it in my book.
Hi @Franky thank you very much for your guide, what do you think about SUNON MF40201V2-1000U-A99 for PSU (with replacement backside) and I am also confused by Hotend cooling, in your post there is 80x80x20, but link leads to 40x40x20/10 fans, also all replacement fans are 40x40.