If you run fans of an MX2, what range of voltages?

NeilFawcett · Post by **NeilFawcett** » Fri Jan 23, 2004 6:27 am

If you have some of the fans in your case running from an MX2, I assume you control their speed by specifying the voltage to them? If so what range can these voltages be from/to?

Johnny · Post by **Johnny** » Fri Jan 23, 2004 7:38 am

I think you can supply from 0 to 100% voltage using the MX2 series, cpu and case fans are normally 12V. you can run them at 5V and 7V, or anything else you wish!.

I assume you control their speed by specifying the voltage to them? If so what range can these voltages be from/to?

yes

FrankFuss · Post by **FrankFuss** » Fri Jan 23, 2004 12:53 pm

The MX2 does not vary the voltage in order to control the fans; it uses Pulse Width Modulation (PWM). In other words, the 12V power is turned on and off at a given frequency so that it is on a certain percentage of the time from 0% to 100%. This is the same type of fan control you would typically see from a motherboard BIOS that controls fan speed.

Johnny · Post by **Johnny** » Sat Jan 24, 2004 5:43 pm

FrankFuss wrote:The MX2 does not vary the voltage in order to control the fans; it uses Pulse Width Modulation (PWM). In other words, the 12V power is turned on and off at a given frequency so that it is on a certain percentage of the time from 0% to 100%. This is the same type of fan control you would typically see from a motherboard BIOS that controls fan speed.

i see thanks fuss

NeilFawcett · Post by **NeilFawcett** » Mon Jan 26, 2004 2:50 am

FrankFuss wrote:The MX2 does not vary the voltage in order to control the fans; it uses Pulse Width Modulation (PWM). In other words, the 12V power is turned on and off at a given frequency so that it is on a certain percentage of the time from 0% to 100%. This is the same type of fan control you would typically see from a motherboard BIOS that controls fan speed.

What would this mean to any LEDs on the fans then?

Paradigm · Post by **Paradigm** » Mon Jan 26, 2004 9:52 am

The other catch with using PWM is that even at 0%, there is still some "leakage" current. This is not normally enough to turn a fan, but it is enough to light up the LEDS. From what we have seen the led fans always have their LEDs on, even when the GPO is "off". But otherwise you don't notice anything in the LEDs.

FrankFuss · Post by **FrankFuss** » Mon Jan 26, 2004 7:49 pm

I am using Cooler Master LED fans and the LED intensity seams to vary somewhat closely with the speed of the fan. My top fan is usually at 0% and I the LED is not lit at that setting.

NeilFawcett · Post by **NeilFawcett** » Tue Jan 27, 2004 9:51 am

FrankFuss wrote:I am using Cooler Master LED fans and the LED intensity seams to vary somewhat closely with the speed of the fan. My top fan is usually at 0% and I the LED is not lit at that setting.

Understandable... But if you set a fan to approx half it's normal speed, do the LEDs even still light up?

Johnny · Post by **Johnny** » Tue Jan 27, 2004 10:27 am

Yes,

The brightness is proportional to the voltage supplied, ie a 12V fan running at 5V will have dimmer leds than if it was running at 12V. I find that my led fans stop but the leds stay lit at very low voltage, albeit v dim .

FrankFuss · Post by **FrankFuss** » Fri Jan 30, 2004 12:26 pm

Yes, the LEDs on my fans are lit at a very low setting.