Does the Seasonic S12 fan controller use PWM?

sipitai · Post by **sipitai** » Tue Sep 20, 2005 10:39 am

Hi everyone,

Does anyone know if the Seasonic S12 fan controller uses PWM (Pulse Width Modulation) to control the speed of the fans?

The reason I ask is because I read that this can cause noise problems with Yate Loon and Nexus fans...

http://forums.silentpcreview.com/viewto ... 796#194796

Also does anyone know if the fan controller provides 12V to the fan connectors for a few seconds when the PSU is switched on (to make sure the fans start spinning), before it reduces their speed / voltage?

Any information would be greatly appreciated.

Thanks!

Oliver · Post by **Oliver** » Tue Sep 20, 2005 1:39 pm

I have no idea for your 1st question.

If I understand the 2nd, well there is a splitter that will just route the wires so you can run a fan off the connector at 5v instead of 12v. ( I forget whether that plugs into the HDD power wires or off the motherboard fan pins, I am not sure where my connector is right now so I cannot check this instant).

sipitai · Post by **sipitai** » Wed Sep 28, 2005 10:30 am

Here is the offical word from Seasonic support:

"The fan control design of the series does not use the PWM rather the linear control circuit, which use the thermistor to drive the continuous voltage."

Devonavar · Post by **Devonavar** » Wed Sep 28, 2005 1:56 pm

1: No

2: No

ultraboy · Post by **ultraboy** » Wed Sep 28, 2005 5:38 pm

I've been using Yate Loon fans with PWM without noise problem.

sipitai · Post by **sipitai** » Thu Sep 29, 2005 10:14 am

Below is some more information from Seasonic support:

Does the fan controller provide 12V to the fan connectors for a few seconds when the PSU is switched on (to make sure the fans start spinning), before it reduces their speed / voltage?

"No. This kind of design will let the circuit layout complex and raise the probability of fault. So there is no consideration for us temporarily."

Are there any known problems using Nexus Real Silent case fans, or low RPM case fans in general, with the Seasonic S12 fan controller?

"If you mean to replace the fan with Nexus one, which is with 1000RPM, it's not recommended. It does not suit for the design of fan controller. If you mean to use the external fan control output, that will be ok."

Is the internal PSU fan controlled differently to the external case fans?

"The external fan control output does not provide thermally controlled function as the internal one."

More info:

"The External Fan Control function provides lower voltage outputs to reduce the speed of case fans and make the whole system even quieter. For Installation, use the case fan adapter to connect between the 4pin HDD connector and up to 3 case fans to reduce noise from your case fans. (The connector marked "H" is for "Full" speed run, the other marked "L" is for "Low" speed run). Please be informed this one does not provide thermally controlled function. And this feature may not be applied to some case fans those can’t be operated by lowering voltage."

Bluefront · Post by **Bluefront** » Thu Sep 29, 2005 11:08 am

PWM is different for every controller, and for every fan. You just never know in advance if a PWM control of fan voltage will make a particular fan click.

If you see a scope with a PWM display, you might be able to understand. The voltage can just turn on/off quickly.....or the 12v can be ramped more slowly. The frequency of these pulses causes the clicking...and some controllers can adjust for PWM noise. I think speedfan can. The T-Balancer can adjust for PWM noise.

The Attenuators I linked to in that other thread work perfect for me....