Can someone tel me how can i change the speed of the cpu fan ?
What port should i use ? :)

Posted on 2002-04-05 08:32:03 by Rosky
I'd suspect it is motherboard specific, and the chances of you weadling that information out of any motherboard maker without a legal task force to back you up is next to nil.

For there to be some definitive way of controlling fan speed, firstly it would have to be a standard option, and secondly done in some standard way. I don't think either is true :(

Posted on 2002-04-05 09:36:22 by Mirno
You need to know what type of hardware monitoring chip your MB have,then look for documentation of that chip(can usually be download from manufacturers website). It?s absolutely possible and I don?t think it?s illegal in any way if the info is public.
Posted on 2002-04-05 10:07:12 by WinCC
If they give the info away it is fine to do, but usually this sort of information is given only under NDA.

Posted on 2002-04-05 10:10:50 by Mirno
CPU Fans are typically (being every Fan I've ever seen) self contained. They have a small circuit within them (about the size of your fingernail) which regulates the coils for rotation. As well as this, most now a days has a signal line to return an analog value that would represent its current rotation rate.

So as i understand your questions, i would say you need to build a new fan.

This is also suported by hardware as they are standardized 'slots' for the fan headers on motherboards, and they are +5V (or +12), Ground, and a Analog Return Signal.

So the best you would achieve in software, is writing another monitoring program.

However, if you are extremely diehard on the idea, you can always create your own hardware (74LS374 tristate Latch on a PCI or ISA bus and you basically have devised your own port ~ need some other circuitry like NAND and NOT gates)

From here the sky's the limit :) (( Its fun stuff tapping into hardware bus's))

Hope this is some help to you..
Posted on 2002-04-06 05:17:12 by NaN
As unbelieveable as thios seems, Microsoft actually has a whole series of API's devoted to the CPU fan. You can read/set the speed and other parameters on it. It's part of the Power API section.

I read some on this a year or so back, sorry, I don't have a link to where I found the info. It's burried somewhere in MSDN.
Posted on 2002-04-07 01:19:36 by Ernie
Following Ernie's tip, i did some searching. The fan related stuff can all be controlled through WMI, but in order to do so you will have to tackle COM :) WMI is installed by default on Win2K, and comes as an add-on for prior versions of Windoze. Unfortunately, there were no clues in the documentation that i scanned as to what API functions were being used by the WMI classes. A quick way to find these APIs out would be to write a quick VB script using a WMI class, then run APIMon to check what APIs are accessed.
Posted on 2002-04-07 19:15:10 by sluggy
I remember something about having to install "LM87" to make CpuIDLE
to report the fan speed. So perhaps a google for LM87 would turn
up something interesting.
Posted on 2002-04-09 12:20:01 by f0dder