Macbook fan always on under bootcamp!

There is no fan control in Windows via Boot Camp. The fans are always on, they just vary in speed depending upon temperature. The hotter the computer gets the faster the fans rotate and the more noise they make.

There's third-party software available for that but I would recommend against using it. All it does is increase the idle speed. It has no control over the fan speed otherwise. If you look for ways to keep the computer cooler that would help - lower the room temperature, improve airflow around the computer, etc. Or use Parallels or VM Fusion to run Windows instead of Boot Camp. Virtualization software runs concurrently with OS X so there's better control over temperature. However, anytime you run processor/graphic intensive software the computer is going to heat up and the fan is going to run faster - and louder.

Windows should not be running so hot that the fan is always on. If I am surfing with lots of Macromedia (Flash ads, UTube) then the fan roars as the CPU heats up, but the fan should go down to zero when there is no Flash running (Google news for example). The indication of a fan always on in Windows is that something is running in the background that you are unaware of and you need to see what it is. Control/Alt/Delete should get your task manager up and you can see what services are running. Google them to see what they are. Often they are harmless or else there is an antivirus task running in the background, but if it is adware or a virus you need to find out how that happened and what to do to prevent it. (lesson: Windows, like watching for tooth decay, requires eternal vigilance)

NA Smith wrote:
Windows should not be running so hot that the fan is always on. If I am surfing with lots of Macromedia (Flash ads, UTube) then the fan roars as the CPU heats up, but the fan should go down to zero

I don't think this is accurate. My fan (according to iStat Pro) runs all the time at 1800 rpm. I think I read somewhere that that is the default speed. Now maybe it's so quiet at that speed that no one can hear it. I certainly can't. When I load my system up with Parallels and Vista, the speed kicks up to as much as 6500 rpm which I'm certain is a function of the increase CPU cycles making more heat to get rid of.

Unfortunately for me (or perhaps fortunately), my hearing has gone South with a lifetime exposure to jet noise, so my Mac fan noise even at high speed is just a gentle hush.

"...the fan should go down to zero..."

I meant merely the noticable sound of it - with excellent hearing I'm hearing zero fan activity most of the time (even tho' as you have pointed out, it must be turning over all of the time, but gently.)

Honestly - when using Windows (on a Mac or not), a person needs to properly check out suspect power usages of all kinds. You'd be surprised with the kind of crap some software manufacturers are draining your machine's resources for (without telling you!)