System Fan 4-pin Acer tc 1660

>>> It's strange because as I said when I boot the pc I see the fan working for 1-2 seconds, >>>

This is normal for the fan to spin up full tilt at boot time to assure overcoming a stalled rotor due to a phenomenon known static friction --- stiction. This results when the fan has been off for long periods of time. It can prevent the rotor from spinning even at lower speeds. It's possible that the Noctua has been sitting around for so long that the rotor can't be controlled any more at lower speeds or maybe its controller is somehow damaged if not recognized in the BIOS. New replacement 80mm smart fans are cheap. If it was mine, I'd order a new smart fan.

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JackE said:

>>> It's strange because as I said when I boot the pc I see the fan working for 1-2 seconds, >>>

This is normal for the fan to spin up full tilt at boot time to assure overcoming a stalled rotor due to a phenomenon known static friction --- stiction. This results when the fan has been off for long periods of time. It can prevent the rotor from spinning even at lower speeds. It's possible that the Noctua has been sitting around for so long that the rotor can't be controlled any more at lower speeds or maybe its controller is somehow damaged if not recognized in the BIOS. New replacement 80mm smart fans are cheap. If it was mine, I'd order a new smart fan.

Thanks for the reply, I apologize for my bad pc knowledge and I'm grateful for the info about fan behaviour at start up! I'm sorry it wasn't clear, the previous pc was only an idea and the noctua fan is new, I unboxed it today (I wanted to build my own pc, I bought some parts but then I found an incredible deal for the tc 1660).
I tried some solutions and these are the results:
-If I set smart fan off in bios, the noctua fan (connected to SYS FAN 17) and the stock fan work flawlessly at max power all the time. Obiouvsly it is quite noisy (I could even accept noctua at max power all the time but the processor one is too noisy)
-If I set smart fan on in bios, the stock processor fan works normally and the noctua fan (connected to SYS FAN 17) works only at startup and then it seems to be died (even in gaming, under load, there seems to be no way to turn it on: maybe the "default curve" of the fan makes it impossible to turn on at the correct temperature?)
-I saw a splitter in the noctua fan package, so I tried to connect it to number 2 in photo (CPU FAN 2), and then i connected the cpu fan and the noctua fan to the splitter. I set smart fan on in bios and now it seems to work: in light tasks only the processor fan works, if I start a demanding game the noctua starts working too (I see it rotates at low or high speed according to necessity, I'm nearly sure the noctua fan has no problem as it is new). In this case I left SYS FAN 17 free without any cable connected.
I found this "expedient" on the internet, I wonder if it is "correct" or not... I saw another motherboard's bios with the specific option to set the fan's curve, for SYS FAN and CPU FAN but unfortunately I can't find anything about the tc 1660's one in bios (exept for the smart fan toggle on off). Should I try anything else with noctua connected to SYS FAN 17 or maybe it's better to leave both connected to the splitter in CPU FAN 2? Thanks for the patience and sorry for my knowlendge: every little help is extremely useful!

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prunemaster said:

what happens if you swap fan headers? 2 <---> 17

I connected the noctua to 2 and the stock to 17. Both of them works, noctua is faster.
I'm trying to open Far Cry 5 as a test.
-The Noctua works connected to 2 and to the "splitter" connected to 2
-The stock fan always works fine: connected to 2, to 17, to the splitter connected to 2.
- The Noctua fan starts at boot and then dies if connected to 17
I noticed that the Noctua always reduces rotation and then gradually stops if not under load in all tests (2-17-splitter, but the main difference is that when connected to 17 it doesn't start if I launch far Cry; when connected to 2 or to the splitter, it starts rotating when I start the game). The stock CPU fan always works and never stops in every test.
It would be great to know what is the better cable connection config and I still don't understand why the noctua doesn't start with the game if connected to SYS FAN 17.

(1) If you disable SmartFan, is the CPUFan speed still displayed?

(2) Is the Noctua 12V on the label?

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JackE said:

(1) If you disable SmartFan, is the CPUFan speed still displayed?
(2) Is the Noctua 12V on the label?

If I disable smart fan, I see the rotation speed of both fans in every connection test (like 2000 and 4000). When I enable smart fan, the one wirith Noctua connected reports N/A. Yes 12V operating voltage on the label.

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prunemaster said:

If I disable smart fan, I see the rotation speed of both fans in every connection test (like 2000 and 4000). When I enable smart fan, the one wirith Noctua connected reports N/A. Yes 12V operating voltage on the label.

But when you swap the fans on the headers, they both do appear in BIOS ?

Yes, if I disable smart fan they both appear (with swap and with no swap, no difference in that case).
Maybe with smart fan on, the minimum RPM provided by SYS FAN 17 is not enough to start the noctua. When I tried playing Far cry with the fan swapped (cpu stock fan on SYS FAN 17 and Noctua on CPU FAN 2) I noticed that the stock fan worked at very low speed, while noctua increased significantly. It seems like SYS FAN 17 doesn't provide any "RPM boost" to the fan connected.

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JackE said:

(1) If you disable SmartFan, is the CPUFan speed still displayed?
(2) Is the Noctua 12V on the label?

Thanks to your scheme I saw the 4 little cables connected to the pins and I finally "solved" by cutting with scissors two of them (number 3 and 4, those were the problem) from an additional exension cable that was in the package of the noctua (I'm not sure this was the purpose of that cable, but after hours of tests this was a good sacrifice). I used that homemade 2 pins cable with only the power supply and now I have the Noctua connected to SYS FAN 17 working flawlessly at max speed always game-ready (it remains extremely quiet and the temperatures are good), and the stock cpu fan connected to CPU FAN 2 working perfectly as I wanted with smart fan on. It's a temporary solution but I'm happy now ahaha

prunemaster said:

maybe with the cpu fan connected on the sys-fan header #17, you can check while the computer is cool and tell what it's minimum speed is.

I have connected and disconnected cables 10-15 times, maybe I'll try next days and see what happens... But even if we suppose it is under the noctua's minimum rpm, I play far cry and the fan doesn't start (the noctua) or doesn't increase rpm (the stock connected to 17) with temperatures near 70 when the cpu 2 fan is near max rpm. There is clearly a problem in the fan activation and "boost" curve; if there is no way to modify the fan behaviour for 17 SYS in the bios exept for the smart fan toggle I can't see how the fan connected to 17 can work as it should.

>>>SYS FAN 17 working flawlessly at max speed always game-ready (it remains extremely quiet>>>It's a temporary solution I'm happy now ahaha>>>

Congrats on being happy. Maybe if you don't hear too good like me, it'll be a permanent solution, But if it bothers you running full blast, maybe switching the 3&4 wires might be a permanent fix depending on if the sensor and control wires for the fan are different from the mainboard. Might work. Might also destroy your mainboard. Thanks for reporting back.

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>>>I'm nearly sure the noctua fan has no problem as it is new>>>

You also might've gotten a brand new lemon. So you might wanna try to splice the sensor controller wire back together. Then temporarily use the CPU FAN connector to see if the Noctua behaves like the CPU fan. Don't load the CPU up. Just see if the Noctua runs at any speeds lower than full tilt.

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JackE said:

>>>I'm nearly sure the noctua fan has no problem as it is new>>>

You also might've gotten a brand new lemon. So you might wanna try to splice the sensor controller wire back together. Then temporarily use the CPU FAN connector to see if the Noctua behaves like the CPU fan. Don't load the CPU up. Just see if the Noctua runs at any speeds lower than full tilt.

Yes the Noctua connected to CPU FAN 2 with the normal 4 pin cable keeps working at low speed without any problem, then it increase its speed under load, a little faster if I start a youtube video (in these tests I see that it is clearly going at lower speed than full tilt, no doubt), significantly faster if I start a game, it simply works as a cpu fan should. Probably the real problem is that the default fan curve for SYS FAN 17 is nonsense and sadly there is no way to change it on the bios. I'm fine with my "brutal canibalization" for now, the noctua is extremely quiet and the noise is more than acceptable for me.

prunemaster said:

@Luke9555
ok, I cannibalized a fan and plugged it in into the #17 sys-fan header.
The exact same thing you reported happened to me.
The fan starts out with normal looking speed.
Then it soon slows down.
and down.
and down.
when it got to around 130 RPM, it went N/A.
and stopped. dead.

I think it's an Acer ACPI bug.
But if that's really their intent, to stop the hdr#17 fan until the box starts running hot, then reporting "0 RPM" would be more reassuring than "N/A".

The sad thing is that a little control panel on the bios would solve the problem immediately. I don't understand the reason to put the "SYS FAN 17" port in the motherboard without any control options on the bios (smart fan curve control would be great, or at least the possibility to have smart fan enabled for CPU FAN and disabled for SYS FAN). I understand this is not a top priced motherboard, maybe the detailed fan behaviour scheme is too much, but a little control panel... Trust me, in game even if the box starts running very hot the SYS FAN 17 gives no speed boost at all. The "cable cannibalization" seems to be the only "solution" for now.