Question related to PWM and DC

[Keita]

Hi guys, I'm currently building my first computer, since motherboard technologies are way different from my first desktop computer (an Intel Pentium III)

the motherboard I got can be configured for fans that work in DC and PWM.

 

I installed the fans (I have no way to go into the bios since I don't have the CPU yet) but when turning the computer on I notice that the 4th fan header

doesn't work. All 4 fans installed are DC only (3 pin) but I wonder if it's not working because the header is in PWM mode or its a broken fan header?

Should a DC fan turn on despite the header being on PWM mode or only works (turns on) when it's on DC mode?

 

Thanks in advance

[LawlBot]

1 minute ago, Keita said:

Hi guys, I'm currently building my first computer, since motherboard technologies are way different from my first desktop computer (an Intel Pentium III)

the motherboard I got can be configured for fans that work in DC and PWM.

 

I installed the fans (I have no way to go into the bios since I don't have the CPU yet) but when turning the computer on I notice that the 4th fan header

doesn't work. All 4 fans installed are DC only (3 pin) but I wonder if it's not working because the header is in PWM mode or its a broken fan header?

Should a DC fan turn on despite the header being on PWM mode or only works (turns on) when it's on DC mode?

 

Thanks in advance

PWM or DC is referring to the fan type...you should be running 3 pin fans in DC mode and NOT PWM

[Keita]

Just now, LawlBot said:

PWM or DC is referring to the fan type...you should be running 3 pin fans in DC mode and NOT PWM

I know, but my question is should a fan work despite the header being on PWM mode? Or do I have to put it in DC mode to make the fan "work"? 

 

I'm just testing the motherboard to see if I should return it because its broken or smth

[W-L]

2 minutes ago, Keita said:

Hi guys, I'm currently building my first computer, since motherboard technologies are way different from my first desktop computer (an Intel Pentium III)

the motherboard I got can be configured for fans that work in DC and PWM.

 

I installed the fans (I have no way to go into the bios since I don't have the CPU yet) but when turning the computer on I notice that the 4th fan header

doesn't work. All 4 fans installed are DC only (3 pin) but I wonder if it's not working because the header is in PWM mode or its a broken fan header?

Should a DC fan turn on despite the header being on PWM mode or only works (turns on) when it's on DC mode?

 

Thanks in advance

I would test it when you have the CPU and everything assembled, but as said for 3 pin fans if you want to be able to control the speed of the fan you should configure it in DC voltage mode. PWM mode on a 3 pin fan will run but only at full speed with no type of control.

[Jurrunio]

11 minutes ago, Keita said:

All 4 fans installed are DC only (3 pin) but I wonder if it's not working because the header is in PWM mode or its a broken fan header?

IF it doesnt work, then either it's turned off in the BIOS or broken. PWM headers control speed with the pin DC fans dont connect to while supplying a continuous 12V through the live pin, which means a DC fan connected to it will go full blast at all times.

[Keita]

Thanks guys, I ended up taking it to RMA, better be sure that it works properly than sorry that i'll come into another issue after the warranty has expired....

[LogicalDrm]

10 hours ago, Keita said:

Thanks guys, I ended up taking it to RMA, better be sure that it works properly than sorry that i'll come into another issue after the warranty has expired....

So header didn't provide power or didn't show up in BIOS? What mobo was that? There are some mobos where they have extra headers which aren't monitored or controlled by mobo. They just provide full 12V power.

[Keita]

6 hours ago, LoGiCalDrm said:

So header didn't provide power or didn't show up in BIOS? What mobo was that? There are some mobos where they have extra headers which aren't monitored or controlled by mobo. They just provide full 12V power.

Yeah, the header didn't have any power, tested it with a voltmeter before returning it. The motherboard is a MSI Z370 Tomahawk, the bios settings allows to control the speed of all fan headers incl the waterpump one but it doesn't allow to power on/off each header, all of them *should* have power for as long as the motherboard is working.

 

It has 4 headers for case fans, one for cpu, one for the waterpump. every single one of them works fine out of the box but the 4th header didn't get any power. If i unplug the fan that was connected there and connect it to any other header while the mobo is running, the fan works without any issue.

 

Edit: I could have kept the mobo and use a spliter instead since it didn't bother me a lot anyways but if it has a header broken who knows what other issue it could have 

[Keita]

Just quick update, I went today to the store and they gave me another MSI Z370 Tomahawk, it had the same issue, they tested the last one they had on stock and guess what, the same issue. *sigh* I ended up exchanging it for an ASUS TUF Z370-PLUS Gaming... I hope I made a good decision.

[IAnthonyFX]

On 6/8/2018 at 5:44 PM, Keita said:

I know, but my question is should a fan work despite the header being on PWM mode? Or do I have to put it in DC mode to make the fan "work"? 

 

I'm just testing the motherboard to see if I should return it because its broken or smth

it would run, you wont be able to lower the speeds (it will always be at 100%) It happened to me, but just use a proper fan header in the mobo for the fan type