Fan power ratings and 'driveability'

jaypers · Post by **jaypers** » Mon Jan 20, 2003 7:05 am

I was wondering if someone might be able to explain something which is bothering me!?

I have a fairly quiet (but no enough!) system and use Speedfan to control my case and PSU fan. I will concentrate on the case fan as an example: I used to use a Papst 8412 N/2GM fan but found that Speedfan could only drive it through a very small range of speeds (hence effectively unusable). It is rated at 0.11A, 1.3W.

I replaced this fan with a Noiseblocker Ultrasilent S2 fan rated at 0.10, 1.2W. This fan works brilliantly with Speedfan which can drive it to almost idle speed up to maximum.

I don't have both fans exact cfm measures to hand but remember the difference is not huge.

My question is why is one fan easily 'driven' by Speedfan and the other not despite similar power ratings? This also applies to the Zalman Fanmate where I found similar results - ie the Noiseblocker went through a wide range of speeds and the Papst didn't.

Thanks!

jp

hyum · Post by **hyum** » Mon Jan 20, 2003 1:14 pm

speedfan is software that utilizes whatever hardware fan controller it can find onboard. thus, how it controls your fan is mainly a questions of what what type of fan control is being used (motherboard depandant) with what model of fan. typical fan control is done by PWM, but there are other methods. one fan may operate better with one method than another. additionally, some fans can operate at lower voltages than other fans, and some have higher startup torque requirements than other fans-

or it could be a combination all the things mentioned above.

ez2remember · Post by **ez2remember** » Tue Jan 21, 2003 12:17 am

SpeedFan is far from perfect, but it is free.. I can't drive the speed of my fans at all, I just rewire all my fans.

SpeedFan will get better, there is still lots of bugs with it and it's not very polished yet.

jaypers · Post by **jaypers** » Tue Jan 21, 2003 6:48 am

Thanks for the replies, what really confuses me is that my Zalman fanmate + other potentiometer based speed control methods have the same problem.

The Papst fan can be only adjusted between say 75-100% speed whilst the Noiseblocker is more like 25-100%. I'm sure it must be something to do with fan differences but how can you tell how easily adjustable a fan is without physically trying? I would have thought that with the power ratings they had, they would have reacted similarly...

By the way I have 2 fans of each and the reaction is the same so it's not to do with the fans being faulty

jaypers · Post by **jaypers** » Thu Jan 23, 2003 6:48 am

Any further takers?

Unless I have missed something obvious in the fan description it seems there is no way of knowing without physical testing?

If that is correct, a thought for MikeC: I was wondering whether this is somehow something that could form part of a future test on SPCR?

Having fans whose speed is easily adjusted (whether by software or hardware) has made my PC much quieter. How about a fan datasheet which would have further info on this? I would have thought this is essential info for many when buying a new fan?

Or am I simply going mad

!?

jp