Fan spin up issues.

[Toxiic]

Hi guys, so I've recently built myself a new Mini-Itx rig and I've been having some issues with the fans that i've installed. In the case I have a NF-P12 and a NF-A14 which is each connected to a noctua Low Noise Adapter and then connected to their Y-Splitter cable(so both are running off the same 4-pin header). I've noticed that whilst my A14 (exhaust) can run fine with no problem, the P12 slightly moves but refuses to fully spin up (kind of jolts forward and then resets).

 

I've noticed that when I increase the PWM / C from say 1.50 to 2.00 that the fan moves slightly further and when I set the header to Full Speed both the A14 and P12 run with no issues. So i'm wondering whether the 4-pin header on my motherboard isn't supplying enough voltage to power both the fans due to them being PWM controlled. Furthermore, would there be anyway to change this as i want my build to be as silent as possible and running both fans at full speed constantly is very annoying.

 

Computer: (main bits) 

i7-6700K

Z170N-WiFi - Gigabyte

Corsair CX500M

Noctua NH-U14S

 

Thank you in advance

[Verex]

Is there anyway you could test the fans out on another build and maybe see if the mobo is causing the issue?

[WoodenMarker]

Are your fans 3pin DC or 4pin PWM?

Moved to Air Cooling.

[Toxiic]

Just now, Verex said:

Is there anyway you could test the fans out on another build and maybe see if the mobo is causing the issue?

I might be able to try on another board tomorrow, good shout.

[RS2007GOD]

Are you sure that header is set to pwm mode not dc?

[Toxiic]

Just now, RS2007GOD said:

Are you sure that header is set to pwm mode not dc?

I hadn't thought about that, Ill double check that now.

[Verex]

Just now, RS2007GOD said:

Are you sure that header is set to pwm mode not dc?

This is most likely the issue if I had to guess.

[Toxiic]

32 minutes ago, WoodenMarker said:

Are your fans 3pin DC or 4pin PWM?

Moved to Air Cooling.

I'm afraid I'm not sure how to check, I can't find any options relating to it in the bios and the Gigabyte EasyTune6 software used refuses to work on my system. Kinda snookered right now.

[LogicalDrm]

9 hours ago, Toxiic said:

I'm afraid I'm not sure how to check, I can't find any options relating to it in the bios and the Gigabyte EasyTune6 software used refuses to work on my system. Kinda snookered right now.

Since you've already set header control from BIOS, its set to PWM. Have you tested both fans on same headers without splitter and without LNA? And since you are using PWM to control fans, do you actually need LNA?

[meenmeen1103]

12 hours ago, Toxiic said:

snip

A LNA is essentially just a in-line resistor between source voltage and output voltage, usually designed for one fan. Splitting out from one into two fans may not be the best idea, as the resistor already gets warm with just the load from one fan (touch the heatshrinked ends of the LNA while the fan/s is/are on to verify). Also, it's not likely you need it anyway with PWM, as PWM is a superior voltage regulation method to a LNA. It pulses the voltage many times per second to give an average voltage lower than the source, instead of just dumping voltage as heat to get a lower output voltage. It's likely that with both voltage reducers the one fan not spinning up only does so because it's receiving too little voltage.

[WoodenMarker]

18 hours ago, Toxiic said:

I'm afraid I'm not sure how to check, I can't find any options relating to it in the bios and the Gigabyte EasyTune6 software used refuses to work on my system. Kinda snookered right now.

It's not an option in the bios. I'm referring to the fans themselves. 

The NF-P12 and NF-A14 both come in either 3pin DC or 4pin PWM.

[Toxiic]

16 hours ago, WoodenMarker said:

It's not an option in the bios. I'm referring to the fans themselves. 

The NF-P12 and NF-A14 both come in either 3pin DC or 4pin PWM.

Both are 4pin PWM

 

23 hours ago, meenmeen1103 said:

A LNA is essentially just a in-line resistor between source voltage and output voltage, usually designed for one fan. Splitting out from one into two fans may not be the best idea, as the resistor already gets warm with just the load from one fan (touch the heatshrinked ends of the LNA while the fan/s is/are on to verify). Also, it's not likely you need it anyway with PWM, as PWM is a superior voltage regulation method to a LNA. It pulses the voltage many times per second to give an average voltage lower than the source, instead of just dumping voltage as heat to get a lower output voltage. It's likely that with both voltage reducers the one fan not spinning up only does so because it's receiving too little voltage.

Thanks for the information, ill check this out when I have time.

 

On 24/09/2016 at 11:32 AM, LoGiCalDrm said:

Since you've already set header control from BIOS, its set to PWM. Have you tested both fans on same headers without splitter and without LNA? And since you are using PWM to control fans, do you actually need LNA?

I will try this once I have some spare time, thanks!

[WoodenMarker]

On 9/25/2016 at 4:15 AM, Toxiic said:

Both are 4pin PWM

You should not be using the LNA if you're controlling the speed from the motherboard. 

[Toxiic]

It seems that the LNA were causing the issues, removed them and both fans are running fine. Thanks for the help guys!