[SOLVED] PWM Annoying noise after switching from DC

longandrew321

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Oct 1, 2017
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So i went into my fan control and turned the full speed mode for my cooler to standard while on pwm. The fans slowed down like normal and it just sounded like more quite fan.

I clicked on DC to see what would happen and it sounded the same

Then i switched back to pwm and this annoying sound starting occuring and I am completely unsure why.
 

Darkbreeze

Titan
Moderator
Did you mean "GQ" or "BQ"? EVGA does not sell an HQ power supply.

Try removing the graphics card and using the integrated CPU graphics output from the motherboard so you can eliminate ANY possibility of it being the fans on the graphics card. I'm sure you know what you are hearing, but it is extremely easy for sounds inside a case to throw themselves around and sound like they are coming from someplace they are not.

Maybe try one of the case fans on the CPU fan header and the new fan on one of the case fan headers on the motherboard to see if the sound stays with the CPU FAN header or moves with the fan.

If the sound remains no matter what fan is connected to the CPU fan header, I'd RMA the motherboard for a bad PWM controller. Make sure as well that you are mounting the fan correctly on the heatsink with the fan blade side of the fan facing towards the front of the case, not the heatsink, and that the fan is securely attached to the heatsink.
 

Darkbreeze

Titan
Moderator
I'd reset the bios to the default settings and start over. PWM fans are not designed to be used with DC setttings, so you MIGHT have damaged the fan especially if it's a cheap model fan with poor PWM design. DC controls speed by changing voltage lower or higher. PWM changes speed but pulsing the 12v signal, not by changing voltage. PWM fans are not generally built with electric motors that are designed for use with variable voltages and much like any motor when there is not adequate voltage or too much voltage, it can harm the motor.

I wouldn't think it would be damaged if you only ran them that way for a short time, but again, it's hard to say and probably depends on the quality of the fan.

Try doing a hard reset of the bios. You'll have to reconfigure any custom settings afterwards.

Power off the unit, switch the PSU off and unplug the PSU cord from either the wall or the power supply.

Remove the motherboard CMOS battery for five minutes. During that five minutes, press the power button on the case for 30 seconds. After the five minutes is up, reinstall the CMOS battery making sure to insert it with the correct side up just as it came out.

Now, plug the power supply cable back in, switch the PSU back on and power up the system. It should display the POST screen and the options to enter CMOS/BIOS setup. Enter the bios setup program and reconfigure the boot settings for either the Windows boot manager or for legacy systems, the drive your OS is installed on if necessary.

Save settings and exit. If the system will POST and boot then you can move forward from there including going back into the bios and configuring any other custom settings you may need to configure such as Memory XMP profile settings, custom fan profile settings or other specific settings you may have previously had configured that were wiped out by resetting the CMOS.
 

Darkbreeze

Titan
Moderator
This is taken from a post by another of our members, paperdoc, and while I'm not 100% certain that everything mentioned is 100% accurate, and neither I think is he, I believe it is at least MOSTLY accurate.

The warning about voltage supply to a 4-pin fan is based on two issues as I understand it. One is that the fan also contains a printed circuit board with components to do several jobs like simulating a commutator and brush system for this brushless motor, generating a speed pulse output, and modulating the 12VDC supplied on Pin #2 with the PWM signal supplied on Pin #4 before sending that to the motor windings. Those circuits require a stable 12VDC supply. Now, earlier 3-pin fans have many similar circuits, too, but they were designed to be used with a variable DC supply on Pin #2, so I have to assume that these components still can work with a supply of less than 12 VDC. How much less? I don't know for sure, but I'd guess they can work down to maybe 5 VDC, and a similar rule would apply to a newer 4-pin fan. A really low supply voltage probably would not damage the fan, but certainly would result is failure to perform as expected.

The other issue is HOW the "reduced voltage" is supplied. Simply providing a fixed DC voltage as a 3-pin fan port would do is one scenario that appears acceptable. BUT the fan manufacturers' warnings I have seen particularly caution you NOT to supply a "reduced voltage" which really is a DC supply already modulated by a PWM signal so that it is NOT a true DC supply. Its is, instead, a train of voltage pulses that switches rapidly from 0 to 12 VDC and back, often at a frequency of 10 to 30 kHz. Such a signal can be used for "normal" DC motors. It cannot be used with the special version motors used for computer "PWM Fans" because the voltage supply contains a lot of noise and potential voltage spikes that could damage the electronic components of the circuits included inside the motor case.
 

longandrew321

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Oct 1, 2017
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Thanks for the reply. Even when I factory reset my bios from the bios it kept my CPU on DC. I reset the cmos battery and the sound still occurred.

Mind you that I have a Cryorig H7

 

Darkbreeze

Titan
Moderator
After you reset the CMOS, you need to go back into the bios and change the fan mode to PWM for any fan that is a PWM fan. Then you need to either select a mode or create a custom curve, and save settings, then exit.

If the fan still makes the same noise after that, I'd replace the fan.
 

longandrew321

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Oct 1, 2017
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I'm going to get a new fan. Should I set the cooler to pwm before I install it or will it default to pwm
 

Darkbreeze

Titan
Moderator
I'd set it to PWM before you install it, just to be safe. I have not honestly seen THIS exact issue happen before, but I've heard of it happening. Sometimes sh, er, stuff, happens. LOL.

Here is the fan I'd recommend throwing on that heatsink.


PCPartPicker part list / Price breakdown by merchant

Case Fan: Noctua - NF-F12 PWM chromax.black.swap 54.97 CFM 120mm Fan ($22.90 @ Amazon)
Total: $22.90
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2018-12-31 02:55 EST-0500


 

longandrew321

Prominent
Oct 1, 2017
21
0
510
0

Hey I used the fan you recommended and just got it today.

However, even after presetting it to pwm the noise still occurs.

Maybe the sound is normal but I have never heard it before.
 

Darkbreeze

Titan
Moderator
It would be very hard for me to say if it was normal or not without hearing it. Perhaps you can record the sound and put up a Youtube recording of it? It's possible there is simply something wrong with your motherboard or power supply as well, or that MAYBE? it's not coming from THAT fan but elsewhere?

What are your full system specs? Motherboard, power supply, graphics card and other part/model numbers?
 

longandrew321

Prominent
Oct 1, 2017
21
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510
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System Specs

8700k
Zotac gtx 1080ti AMP! Edition
Corsair Vengeance LPX 3000mhz
Asus B360-H Motherboard
PSU: EVGA 650 HQ Gold Power supply

I also tried turning off both case fans and they are not the source
 

Darkbreeze

Titan
Moderator
Did you mean "GQ" or "BQ"? EVGA does not sell an HQ power supply.

Try removing the graphics card and using the integrated CPU graphics output from the motherboard so you can eliminate ANY possibility of it being the fans on the graphics card. I'm sure you know what you are hearing, but it is extremely easy for sounds inside a case to throw themselves around and sound like they are coming from someplace they are not.

Maybe try one of the case fans on the CPU fan header and the new fan on one of the case fan headers on the motherboard to see if the sound stays with the CPU FAN header or moves with the fan.

If the sound remains no matter what fan is connected to the CPU fan header, I'd RMA the motherboard for a bad PWM controller. Make sure as well that you are mounting the fan correctly on the heatsink with the fan blade side of the fan facing towards the front of the case, not the heatsink, and that the fan is securely attached to the heatsink.
 

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