Question about cooling fans (1 Viewer)

[Keith Mickunas]

I'm wondering if anybody knows how the 3-wire cooling fans that are pretty much standard work. I see that some are rated at different RPMs and CFMs. Who controls how fast the fan goes, the MB or the fan itself? If I replace the fan in a PC with one that is faster or quieter, or whatever my goal is, will the fan speed increase based on the system temperature only, or does the MB sense the temperature, and set the fan to a certain voltage regardless of the fans rating?

My specific problem is that I want a quieter fan in my Shuttle PC. The PC is one of those little systems Shuttle makes, the SK41G, which only has a small fan for the power supply, and one 80mm fan for the rest of the system. One of those fans is real noisy, and I'm hoping it's the 80mm since I can easily replace that one. But I need to be certain that the system will continue to cool properly with a different fan because that one fan also cools the heat sink on the CPU.

Another problem I have is I believe my modded Tivo is overheating. I'd like to replace that fan, and in that instance the noise issue is not a factor. But I need more cooling because the Tivo acts up even when it thinks the temperature is 37C, which is in it's normal operating range. I suspect that the drives are getting to hot, but the rest of the system is ok, or something like that, and so the system doesn't realize it's too hot. Seems strange, but if I remove the cover it drops to 34C and all is fine.

Both the Shuttle and the Tivo use the standard 3-wire connections. I'd like to find a good fan for the Shuttle that will cool it as much as needed, but be really quiet, and another fan for the Tivo that will basically run all out all the time and keep it real cold. Any suggestions, comments, or advice is welcome.

 

[JamesHl]

The speed is generally determined by the fan, but some motherboards and power supplies can exercise control over the fan based on the temperature.

 

[Glenn Overholt]

Right. The three wire fans with the small connectors that plug into your motherboard are controlled by the motherboard. Some run at a set speed while others will slow down if your system is cool enough.

In any event, if you pop the case open, disconnect the 'noisy' fan and turn it on for just a few seconds, and you will know what fan is the noisy one. Try to find fans that run around 30db, as most are in the 40's, and those you can hear.
I'd leave the fans that are in your system there, and just get some more. If you have a spare connector (large 4-pin), you can plug it into that. If not, get a 'Y' connector.

They are easy to mount too. You can get 2 small right-angle brackets from any hardware store and drill two holes in your case somewhere and mount it just about anywhere you want to.

Glenn

 

[Keith Mickunas]

Thanks for the info. I've dealt with building PCs quite a bit, and have some of mine loaded with fans. But in this case I'm dealing with some specific installs that have different requirements. The shuttle case is tiny, and doesn't have room for extra fans, and I want it quieter because it is placed in the family room. I'll do what you suggest and try unplugging it when it makes a lot of noise and verify it's the case fan and not the power supply.

On the Tivo I've found some more info. The tivo community forums were down for a bit when I originally posted this, but now they're back up. In my case the Tivo noise levels don't matter cause all my A/V gear is in a seperate room from the theater. It supplies one 7 volt fan on the motherboard, also it only uses two pins but people have replaced it with three pin fans because the third pin is the one that tells the MB the current speed. If you use the hard drive connector it bumps the fan up to 12volt, so that's what I need to do there. I'm going to hit a computer store tonight and find a high capacity fan that can run on 12-volts and give that a try. Some of them come with a temperature sensor that you place in the PC, if I put it near the HDs, it should run pretty much all the time.

Now if I can find a fan that truly is high flow and quiet for the shuttle, I'll be happy.

 

[Scott L]

All you need is a fan speed controller. I use one of these and a resistor adapter for another fan in my HTPC and each work great.

 

[Chas_T]

Keith,

It was necessary for me to add fans to a few of my pc's as in the summertime, the boxes became quite warm. One even fried a MB before I added the extra cooling, but it was under warranty so I was lucky.

I just added an extra fan or two to both of these and use Mother Board Monitor, which has a speed control function in the software if I recall. I have not used the speed control on the software, but I think it may be something to look into if you have not already.

http://mbm.livewiredev.com/

I'd think that hardware here would be a better choice, but perhaps the software may be an option too.

Charles