Controlling fans

Tumlehund · Post by **Tumlehund** » Wed Nov 30, 2005 12:47 pm

I got my mind set on a P180 and I'm wondering how to control the speed of the fans (both on the case and CPU). It seems there are several options:
- Asus Q-Fan
- Speedfan (software)
- Zalman Fanmate2
- other?

I guess the best way is to let the fan speeds rise and fall according to temperature level?

I'm planning to use a number of Papst 4412F/2GLL - 1200RPM, 18dBA.

datapappan · Post by **datapappan** » Wed Nov 30, 2005 1:22 pm

Depends on how you're gonna use it. Controllers that ramp the speed can give annoying revving up and down. Temperature control with threshold temp sometimes does not have the proper range (I have BIOS Fan EQ that works with 60% and 100%, I would like it to go down to at least 40%). Rheobus/Fanmate works best in a low power system, where you can set amd forget the fan speed.

Roundup:
Continual thermal control - Bad, because of constant speed changes
Threshold thermal control - Good for gaming/video editing etc.
Manual speed control - Good for low power systems (Celeron)

/ datapappan

PS. FanSpeed can be set to work OK if you make the step value as large as your desired range, e.g. minimum 40%, step 60%, makes it toggle between 40 and 100.

PPS. For my board you have to disable the ACPI reading of Fanspeed, it seems to interfering with the BIOS function, halting the refresh of the thermal diode.

Aris · Post by **Aris** » Wed Nov 30, 2005 1:50 pm

if your going to use a fan controller, make sure its analog. the digital or PWM models tend to cause fans to make excess noise/vibration or clicking that you wouldnt normally get with an analog controller.

heres a good fan controller ive found: Maelstrom Mini

stromgald · Post by **stromgald** » Wed Nov 30, 2005 2:00 pm

Datapappan explains it very well, and I think that threshold thermal control is probably best. Its automatic so you don't have to mess with it when you fire up a game, and you don't get constant speed changes. I'm not sure how you would get continual thermal control unless you get an thermally controlled (TC) fan with a thermisistor. These are quite common on Dells and HPs.

With the Papst which aren't TC fans, I think ASUS Q-fan or Speedfan would be best. IIRC, you're building a fairly high-end system which will most likely be gaming/encoding (too lazy to find your other thread), so you'll probably want automatic control. Personally, I'd stick with the ASUS Q-fan. It won't go down as much as the Speedfan software, but its already in the BIOS, so its one less thing you have to install/configure. If it turns out to be too noisy for you (doubtful, undervolted Papst in a P180 should be almost silent), you can always download and install Speedfan to slow it down even more at idle.

Tumlehund · Post by **Tumlehund** » Wed Nov 30, 2005 2:20 pm

Thanks for all the input, I relly appreciate that!

OK, so threshold thermal control seems to be the way to go. But does Q-Fan provide this? Or do I need Speedfan to do this?

Also, stromgald, you talk about undervolting the fans. How do I do that? Do I need the Fanmate2 to do this?

stromgald · Post by **stromgald** » Wed Nov 30, 2005 3:25 pm

Q-fan and Speedfan use threshold thermal control. When the temperature reaches certain 'threshold' levels, the power supplied to the fan will jump up to a pre-definied level and the fan speed will increase accordingly. It works the same way when going down: as the temperature drops past the 'threshold' temperature, the fan will slow down. Undervolting fans just means you aren't giving the fan its full 12 volts to slow it down. All the methods datapappan mentioned are consdiered 'undervolting' a fan.

Big Fat Duck · Post by **Big Fat Duck** » Wed Nov 30, 2005 8:30 pm

i dunno but my lanparty ultra d has a config in the bios that lets you set the threshold of the rpm speed up area. like if i set the "fan off" option to <25c and "fan full" at 55c, the mobo scales the speed percent by percent..

at least i think

Tumlehund · Post by **Tumlehund** » Thu Dec 01, 2005 2:09 pm

Thanks! Just making sure I understand this...

If I use Asus Q-Fan, this is considered undervolting, correct?

I do not need Zalman Fanmate to undervolt, since I can use Q-fan or Speedfan, correct?

asianx13oy · Post by **asianx13oy** » Sun Dec 04, 2005 8:12 am

this is correct. any way of slowing the fan down would be undervolting it. also, jsut a reminder. you can have speedfan undervolt WITHOUT the thermal threshold control. i.e. you can have speedfan set ur fan at 7v and leave it there, no matter how hot ur comp gets. although i wouldn't recommend this, but this would get rid of that annoying ramping up and down of the fans if ur sensitive to that kinda stuff.

sorry for the thread hijack, but i have a relating question of my own (i was about to start a new thread before i found this one...)

many people on this forum speak of PWM as a way to control the speed of your fans. to my knowledge, PWM are the new 4-pin fans that require a new signal to more efficiently control the speed of the fan. but it seems
that PWM fans were mentioned on this forum a long time ago (such as that sticky about good 120mm fans) BEFORE PWM fans actually came about. also, it is stated that PWM is generally not suggested since it makes the fan louder. i was just wondering if maybe they referred to using speedfan (or other such software) as PWM. so i guess basically what im asking is...does using speedfan make your fan rattle or produce other noises?

EDIT: i found this in that 120mm fan article:
"Basically instead of decreasing the voltage from 12v (which would be called undervolting), PWM simply pluses 12v. So the fan is getting 12v or nothing. The determining factor for the fan's speed is how long 12v is left on/off. Some fans don't take to well to this non-steady stream of current. "

now my question is...do the 3 pin fan headers on motherboard use this PWM, so in essense, is speedfan controlling the fans with PWM?

datapappan · Post by **datapappan** » Sun Dec 04, 2005 11:13 am

No, Speedfan doesn't necessarily do PWM, it depends on your MB. It hijacks th MBs ability to control fan output, which usually is done first via PWM to get the full 0-12Vrange, and then attenuates the signal with capacitors to smooth it - in essence 0-12V voltage regulation with low losses.