So, is there any cheap way to do this with parts from say Radioshack?

perferably at a specific temp

would a cutting off a thremoresistor from a fan work?

just for one fan, it's part of a plan

Well, I don't know how cheap you are, but you might consider the NMT-2 or NMT-3 together with a Nexus fan. The fan never really turns off, but they run the fan at 5V below 30C or 28C respectively.

This Akust device will do it.....you set a temp and the fan turns on when the temp is reached, turns off when the temp goes down. Uses a long remote sensor wire. Nice small device with a temp read-out.

Link

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that's interesting, may be perfect for what I need

though, I just realized that once it turns on a fan, and it lowers the temp by say 1C and the temp goes up again, the fan turns on...etc

is there any way to prevent this?
EDIT instead of placing the sensor right on the GPU heatsink (VM-101), perhaps placing it next to it, in free air, where the temp difference isn't as senstive

actually, I might just use a simple switch to turn on the secondary fan for gaming, but it would be nice to do it automatically

Well that's something you have to experiment with.....say set the temp turn-on point slightly lower than that spot will be under heavy load with the fan going. That way the fan turns on as the temp rises, but turns off only when the load is removed. There are other ways....

your morther board may have the ability to control fans.
what MB do you have.

my MB (MSI pt880 neo) does not have the ability to control fans


Bluefront - that's a great point, would you happen to know how the Akust thermocontrol works?

as when it turns on a fan, it merely completes the circuit? so that the fan is already at a specific voltage (a la fan controller)

It connects to a molex connector....the fan gets 12V when it turns on. If you want to run less voltage, you would need to have a fanmate or a resistor between the Akust and the fan.

Judging from your system specs (P4 Prescott & ATI 9800 Pro), I believe its cheaper and easier to just get a new motherboard that has the ability to control fan speeds using SpeedFanor some other software.

Here is a list of MSI motherboards that you can change clockspeed using SpeedFan.

I think Prescott & AGP slot motherboards will cost around $50 dollars, compare to $10 per fan controller or $30 per 5.25" front load fan controllers.

Perhaps I am mistaken, (or maybe you run Linux) does your board have core-cell?
If it does it should have a fan control utility…

already have everything I need for the project, Sunbeam fan controller
just finished reinstalling everything, don't want to again
the Akust thermometer is just an idea that is being considered



tried that already, I even googled my board and came across similar problems