# funny Chassis1 RPM speeds



## stteng (Dec 17, 2009)

The PC system that I am talking about is one that I & my father put together from scratch. It has an ASUS P5K motherboard running a Intel Core 2 Duo E6750 CPU. Its OS is running Windows XP Pro on it. The case that is being used is a Sonata III case. 

I recently replaced the Sonata III case original fan since it stopped working. I replaced it with a Silenx IXP-74-14T iXtreme Pro 120mm x 120mm x 25mm 
case fan with Thermistor. Everything looked fine at first. Using the ASUS P5k's Probe II's monitoring software, I found that the CPU RPM is about 1767 RPMish. The CPU's temperature is from 25 to 34 degrees Celsius. The ASUS motherboard's temperature is about 34 degrees Celsius. The Chassis1's RPM (Silenx IPX-74-14T's three connector is connected to my ASUS motherboard's three Chassis1 connector.) was about 930 RPMish. Now even though the CPU's RPM is about 1767 RPMish, the CPU's temperature is about 25 degrees Celsius, and the Motherboard's temperature STAYS at 34 degrees Celsius, the Chassis1's RPM (Silenx IPX-74-14T's RPM) intermittingly drops down to 0 RPM and then goes up to 25700 RPM and down to 0 RPM and up to 48100 RPM and then stays about 855 RPMish but then jumps up to some high RPM value and then down to 0 RPM and then back to 850 RPMish. The cycling up and down of the Silenx fan happens intermittingly!

NOTE: My original Sonata III case fan had been connected to the Molex connector of my BFG Tech power supply (power supply that came with Sonata III case was replaced by BFG Tech BFGR800WPSULE 800 W power supply since Sonata III original power supply died on me) so there was NO Chassis1 RPM sensor. 
NOTE: Now the Silenx fan uses the Chassis1 fan's 3 pin connector on my ASUS P5K motherboard so that PC Probe II NOW has an sensor entry for my Chassis1 case fan. My Silenx fan is connected to the Chassis1 3 pin connector on my ASUS motherboard. 

Note the original Sonata III case's power supply was replaced since it burned out. The original Sonata III power supply was replaced with a 800 W BFG power supply. ;


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## Wrench97 (May 10, 2008)

Try using the thermistor on the fan only and hooking the fan directly to a spare molex connector from the power supply.
I think the 2 speed controls are interfering with each other.


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## stteng (Dec 17, 2009)

The model number for the BFG Tech power supply is BFGR800WPSULE. The original Sonata III case fan was connected to a molex connector from the BFG Tech power supply NOT to the 3 pin Chassis1 connector on my ASUS motherboard. There was NO sensor reading for the Chassis1 fan with the original Sonata III case fan. 

What is going on with my Silenx case fan? Why does its RPM drop down to 0 RPM and back up to a high RPM value and then back down to 0 RPM and then up to 855 RPMish intermittenly?

Thanks
stteng


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## stteng (Dec 17, 2009)

If I connect up my Silenx fan directly to my power supply using its Thermistor to control it, then obviously the Chassis1 sensor will be 0 RPM. 

If I keep track of my CPU temperature/RPM, Motherboard temperature making sure that they are low and stay constant so that I can see that my Silenx fan is working fine, then will that be OK?

stteng


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## Wrench97 (May 10, 2008)

Yes I rarely use the Chassis Fan header any more, put the temp probe in the area near the ram(usually the hottest) and watch the temps.


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## pat mcgroin (May 1, 2009)

Ok I may have a reason.
Lookin throught the manual the 4 fan connectors use the Q fan feature.
The Q fan adjusts the both CPU and chassis fans according to system load.

They are adjustable in the bios.
page 4-29 shows where in the bios.
http://www.manualnguide.com/manual-get/8931/
You should be able to change the profile and make it stop doing that.

This caught my attention because I have one here that Im getting ready to put together.
Hope this helps.


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## stteng (Dec 17, 2009)

How do I use the Q-Fan2 feature along with the Thermistor sensor? 

I am just connecting my Silenx case fan directly to my power supply and using the Thermistor. I need to ask Silenx how I should mount the Thermistor? 

I was wondering if I need to use a non-Thermistor fan with the Q-Fan2? That means that I need remove the Thermistor fan, exchange it with a non-Thermistor fan, and then mount the non-Thermistor fan using the Q-Fan2 from the P5k motherboard. 

Which method should I use? I need to ask Asus technical support this question!

Thanks
stteng


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## pat mcgroin (May 1, 2009)

Im not sure that you can.
I think what is happening is the Q-Fan is getting a temp. reading from the MB and then controlling the voltage to the fan header.

It would seem that you have 3 options.
Either hook your new fan independently to the PS and use its thermistor and have a zero reading.
Get a non thermistor fan.
Lastly set the Q_Fan to full power in the BIOS and use the new fan and thermistor for control and Asus probe for temp readings


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