New 4-in CPU cooling Fan won't run right!!....

[stedyone]

Hi all, I have a new ECS GF8200a mobo with a rosewill HUGE cpu fan that has the 4-pin SMART power connector. When the system posts the fan spins and runs for about 2 mins after posting then it quits. I know the fan motor is working because of this. I think I have a BIOS setting that controls the CPU fan speed. The CPU seems to run hot (around 52 C) and yet the brand new CPU fan will not kick on regardless of the fan control SMART BIOS settings. You are supposed to input a temp like 45 C and the fan controller should try to attain that temp. It's not working. When I have the stock CPU heatsink and fan with only 3-pins in the power cord it runs the whole time loud as all heck!

The CPU is a brand new AMD BRisbane 5400 2.8 64 X2 Black box. I have had a support ticket in with ECS for a week!

I would certainly appreciate the help here.

-stedyone

[Nelson37]

Fastest and easiest test is to put the fan on another four-pin board, or try a different four-pin fan on this one. You could test with one of them-there electrical multimeters, but they might not find an intermittent problem. Using KNOWN GOOD similar components will ISOLATE and IDENTIFY the problem, and such tests have never failed to be sufficient evidence to obtain an RMA for replacement.

Reading a LOT of reviews seems to indicate that Rosewill might have some quality-control problems. I have never used any of their products nor even seen them in the field, so I have no personal experience on this company. I have no intention of purchasing anything they make any time in the near future, nor would I recommend them to a customer.

Try cranking the temperature setting way down and see if the fan runs at all after bootup. Could just be a badly-calibrated temperature sensor.

[redwudz]

That's not a "SMART' power connector, that's a PWM connector. (Pulse Width Modulated) There are four wires attached. The white( Or black) and the red are the + and - voltage for the fan. The yellow (Usually) is the tachometer to read the fan RPM. The last wire (Blue?) is the PWM control.

PWM works by sending a variable width voltage pulse to the fan motor, giving very precise control of the fan RPM. You would need to enable PWM in the BIOS for the fan CPU setting for it to work. You might also want to shut off the BIOS CPU fan low RPM warning. With some of my MBs, the PWM CPU fan will start for about 2 - 3 seconds, then stop and you will hear the fan RPM buzzer. This is because the CPU temp is low. As soon as the temp comes up a few seconds later, the fan will come back on.

Cheaper fan controllers just use a variable voltage, but if the voltage and the RPM are set too low, the fan can't start. PWM can control the RPM all the way down to zero RPM and up the the max RPM.

Usually, though, if you want better cooling, turn off the PWM feature and use voltage control or just run the fan at full RPM all the time. Those settings should be in BIOS. PWM is mostly a energy saving feature and also makes the CPU fan quieter.

If the fan isn't performing properly with the PWM setting selected in BIOS, you may have a bad fan. If you hook it to a two pin connector it will run full speed with no control or tachometer reading. A three pin connector will make it like a voltage controlled fan with tachometer reading. The four pin is for PWM. Most PWM connectors are keyed so they will work properly with a two, three or four pin connector.

[stedyone]

Very good reply redwudz! Thank you.

[stedyone]

Update: the fan checked out fine by plugging it in on another header post. It ran fine at full rpm (2000rpm). I wanted to plug it in on the CPU-Fan header as I thought it could still be controllable through BIOS. It would only work full RPM like a regular fan when I pulled out the 4th pin from the plug, i think it was the green lead. Now it keeps my cpu at -7 C. All I need to do now is overclock it from 2.8 stock to 3.0. That's my goal.

[redwudz]

If the fan noise level at 2000RPM isn't objectionable to you, should work fine. My Intel Q9300 runs at 3.3Ghz from the stock 2.5Ghz, so a 800Mhz OC. The CPU idles at 40C. Since I mostly encode Blu-ray to MKV with it (~6 hours ), I run the CPU fan at max. But the video card fan puts out as much noise. Again, make sure you have good airflow in your case and you shouldn't have any problems.

You should have been able to change the CPU fan to full RPM in BIOS by disabling the CPU 'Smart Fan Control', but your BIOS is fairly limited on CPU fan settings. You might look into a Gigabyte MB for your next build, they have quite a few more options in fan and CPU settings, both for AMD and Intel CPUs.