Temp control; variable speed fans

[rhaytana]

I'm planning to build a PC in early '05. I've narrowed my choices re case, processor, mboard, hard disks and so on ... but am still pretty clueless as to how to regulate temps inside the case.

I know I can install fans on the case to bring air in and send it out. What I don't know is how to regulate those fans. I'm assuming that without some sort of regulation, I'll get the same fan speed and ventilation on a December morning as on a July afternoon.

My Dell desktop has no fan noise on cold days and sounds like a little buzz saw when it's hot. If I'm building my own PC, how do I get variable speed control over cooling? It could be done automatically, or I'd be happy to turn a knob to crank up the fan revs myself.

If there's an article about this somewhere online, and anyone has the link, I'd love to see it. If anyone wants to recommend specific products, I'm interested in that, too.

Thanks.

 

[Crashman]

You can get variable speed, thermostatically controlled fans. Those have a thermister and respond only to air temperature, not teperature of any given parts. A smarter way to controll fans is with a BIOS that can adjust fan speed in response to chipset temperature, and CPU fan speed in response to CPU temperature. Whatever you do, it will work.

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[rhaytana]

Thanks for answering. Here's a follow-up question:

Can most new BIOSs adjust fan speed in relation to temperature? If so, will the motherboard also include connections to the fans that tell them when to speed up and slow down? Or would I need to buy an additional piece of hardware to sit between the motherboard and the fans?

I know I'm getting real nitpicky about stuff I haven't bought, but that's how I think I ought to go: try to find out as much as possible in advance, so I don't tear out my hair once the components arrive.

 

[Crashman]

Motherboards that can control fan speeds do so by changing the voltage on the 12v fan line.

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[rhaytana]

I shoulda thought of that! Thanks; mystery solved.