Precise Auto Fan Control...another option.

Bluefront · Post by **Bluefront** » Sun Jan 02, 2005 6:13 am

Maybe I'm too picky...I admit to that. But I'm trying for the lowest CPU fan speed under idle conditions, and at the same time want the fan to speed up under max CPU usage, keeping the CPU temp under 50C. This is a P4-3.2. Sounds easy, right?

The problem is I want this control to be automatic, and Speedfan won't work on this motherboard. I tried a Globe fan S12025 12L-3M, an auto control fan with a long sensor wire. Problems...this fan won't go below 1400rpms, so I lowered the voltage to the fan using a pwm fan controller. This works to lower the voltage enough to maintain an acceptable idle speed....about 1000rpms or so. More problems....I cannot find a sensor location that speeds the fan up enough to maintain a max temp under 50C.

I tried many locations, settling on a spot under the heatsink base-plate next to the edge of the CPU. This location only speeds up the fan about 100rpms from idle to max....not good enough.

I need a controller with a different temp/rpm curve, or a thermal control fan that speeds up more with a reduced hi/lo temp spread. The T-Balancer controller might do this, but it's digital sensor would never fit in the best spots on this heatsink. I suppose I could also buy the add-on analog sensor package with the smaller sensors....but that would end up costing $100 or so to control one fan.

What are my alternatives, using my current heat-sink (Silverstone NT01)....which I'm not changing cause it works so well. Argggg.....

Post by **Ralf Hutter** » Sun Jan 02, 2005 7:31 am

Have you thought about using a different board, one that Speedfan works on? Haven't you spent a lot of time and energy getting basically nowhere so far?

My 2¢, FWIW.

Bluefront · Post by **Bluefront** » Sun Jan 02, 2005 8:38 am

A different board would do it but.....When I looked for this board, I needed one with a horizontal CPU frame mount, located in a certain position to enable the use of the Silverstone heatsink. Which then turned out to be a bear to install. In other words, I've gone too far with this setup to start over.

Right now I'm considering using a DigitatDoc 5 (which I have) to turn on a secondary CPU fan at high temps. This might work ok. I'm working on it now.....

Bluefront · Post by **Bluefront** » Sun Jan 02, 2005 2:10 pm

For now the problem is solved. I attached a slim-line 80mm fan under the heatsink. It'll turn on (undervolted) at aprox 40C....a temperature I can only attain with benchmarking. I've used a DigitalDoc5 for this technique before...so I know it works.

The fan is attached using nylon cable ties through the fins, and four rubber grommet/spacers. No sweat...

photo

greeef · Post by **greeef** » Sun Jan 02, 2005 4:58 pm

http://www.bit-tech.net/article/51/1

is that helpful? Should be able to alter a few values to adjust the range, though a logarithmic curve would be difficult to manage.

MagnusT · Post by **MagnusT** » Sun Jan 02, 2005 10:21 pm

The T-Balancer with four analog sensors and no digital ones is only 6 USD up from the digital sensor version. And in addition you get sensor hub with power-off ability + water cooling expandability + still the possibility to add digital sensors whenever you feel like it....

Just so you know....

Bluefront · Post by **Bluefront** » Fri Jan 07, 2005 4:37 pm

Here's another option based on the Globe 120mm fan with the long sensor wire (S1202512L-3M). Funny I never thought of it before....and I never saw it used before either.

You control the voltage going to the fan (like I am) using some sort of fan controller. You move the sensor around to a location that heats up the highest under max CPU usage. You adjust the ldle fan speed (using the fan speed controller) so the fan speed increase is enough to compensate for normal usage.

Then.....You splice into the sensor wires, leaving the sensor connected, and run the two wires to a simple off/on switch on the front bezel of the case. Turning this switch on, shorts the sensor wires, and forces the fan to it's max rpm, depending on the voltage you're suppling to the fan. Sort-of like a turbo cooling switch. With this switch off, the thermal controlled Globe will work normally.

Now if you want to get fancy, instead of a simple off/on switch, you use a DigitalDoc5 and a small 12v relay (Radio Shack), to automatically switch your fan to max when a certain temp is reached. Basically this is a hardware-based replacement for Speedfan. Heh....

MagnusT · Post by **MagnusT** » Fri Jan 07, 2005 5:24 pm

A fan suddenly jumping up in speed with a relay can be quite annoying compared to a fan that ramps up slowly... But this opinion is surely extremely individual

I still have my ancient homebuilt two-speed temperature controlled relay thingy in a drawer somewhere. Was great at the time but I wouldn't use it today with all the better options around

Cheers!

/Magnus Thomé