My new Dell Optiplex 960 has a really loud fan. I hear that the 760 had some bad fans with the same problem. I've had no luck contacting dell via email or chat (I'll try calling them later this week).

Just wondering if anyone had any solutions other than those in the Question on the Optiplex 760

3 Answers 3


SpeedFan may be able to reduce fan noise:

SpeedFan is a program that monitors voltages, fan speeds and temperatures in computers with hardware monitor chips. SpeedFan can even access S.M.A.R.T. info and show hard disk temperatures. SpeedFan supports SCSI disks too. SpeedFan can even change the FSB on some hardware (but this should be considered a bonus feature). SpeedFan can access digital temperature sensors and can change fan speeds accordingly, thus reducing noise. SpeedFan can find almost any hardware monitor chip connected to the 2-wire SMBus (System Management Bus (trademark belonging to SMIF, Inc.), a subset of the I2C protocol) and works fine with Windows 9x, ME, NT, 2000, 2003, XP and Windows Vista. It works with Windows 64 bit too.

  • I haven't yet tried this but it looks like it does exactly what I need. Feb 13, 2010 at 2:25

You can change to Dell part no : R434D (Thermal Sensor Cable)


you can change only the electronic transistor 2N3904 which is the sensor.

  • Not certain if this is important, but there are two of these sensors. On mine, the front sensor is labeled 2N3904-C10 and the rear is labeled 2N3904-C42.
    – Parker
    Oct 16, 2018 at 17:17

Dell Optiplex 960's (and other Optiplex models) are normally supposed to run quiet with the fans at low speed, though this can be bypassed in the BIOS with the "Fan Control" setting, which runs them at high speed all the time. The fans can be quite loud at high speed.

Also there are two temperature sensors on the 960 that I am aware of. If the cables to these sensors are disconnected or the sensors are damaged, the Dell hardware will run the fans at high speed as a protective failure mode.

One thermal sensor is on the front of the case and measures intake air temperate for the CPU cooler. The plug for it is near the PCI slot and buzzer. The second sensor is on the power supply, and the plug is near the back of the LAN socket.

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