I installed a Scythe Shurinken 2 Cooler CPU on an old Intel DG31-PR motherboard, LGA socket 775, the processor is a 95W Intel Core 2 Quad Q9500 and the BIOS installed is latest existing version PR0071. BIOS is not recognizing PWM when I connect to CPU Fan, speed does not vary, it is fixed at minimum speed. I've already tested the cooler cable and the four ways are 100%. When I plug it into the Sys Fan, then the BIOS recognizes and speeds up keeping around 1700 RPM, but it's not enough for this processor, in this rotation the temperature drops to just 50° and the motherboard registers 68° on average. When I plug the original Intel CPU Fan into the CPU Fan, the BIOS recognizes and maintains the rotation around 1000 RPM. Do you know why this card doesn't recognize the PWM of this cooler? I also plugged a Noctua NF-R8 Redux 1800 with PWM into the CPU Fan of this board and didn't recognize it either, that is, the problem is not a cooler, but the motherboard that doesn't accept any cooler other than Intel's. I have two Intel DG31-PR motherboards and this problem happens on both. Is there any way to resolve this? Buying a new motherboard would be unfeasible, as it would also need a new processor and new memories, it would be very expensive, especially in Brazil with the US$ 5.40 price. I need a solution without discarding the board, can someone help me?
The Q9500 is not a supported processor for your board:
Doc (not an Intel employee or contractor)
[Windows 11 is the new Vista]
Sorry, it's a Q9505. But at no point did I mention that I had a problem with the processor. The other machine has an E7500 and both are running perfectly. This cooler incompatibility has nothing to do with the processor.
First of all, the PWM signal is an output from the motherboard. It is the duty cycle of the this PWM signal that determines what speed the fan should run at. So, putting this in proper perspective, it would be the cooler's fan failing to properly recognize and react to the PWM signal from the motherboard, not the other way around.
Secondly, do not plug the CPU cooler into the secondary fan headers. These fan headers are not reacting to processor temperature change and thus will not speed up the fan if temperatures dictate. Further, plugging a 4-wire fan's cable into a 3-wire fan header means that the fan will not receive the PWM signal (it's delivered via the 4th wire in the cable).
Third, have you explored the possibility that the fan speed is not being varied because the processor is simply not getting hot enough to warrant any higher fan speed? There is a scene in the board's BIOS setup where you can monitor temperatures and fan speeds and can configure the response curve (minimum temperature, minimum duty cycle, maximum temperature, maximum duty cycle, etc.) that is desired.
Hope this helps,