My experience is that the Opt fan connections, except for CPU Opt, run at minimal speed unless you have a sensor cable connected to the associated header, and the sensor stuffed into a hot place. Also, the Opt fan setup has a minimum warning speed of 1200 RPM. The CPU and Chassis fan connections allow down to 600 RPM without warnings. Look on the Probe II Fan Speed tab for these settings.
Now, the Asus Store lists the optional sensor cables, but seems to be perpetually out of stock. I got a bag of ten of the things on Ebay for something like $15, including shipping (USPS). You can only hook up three. However, I have seen warnings that the sensor element can be screwed up, so it's probably good to have spares.
The whole Probe and Sensor software arrangement is kind of irritating to me. My previous Asus board had earlier versions which ran independently. PC Probe corresponded to the Sensor panel on the Crosshair V Formula Z board. I had it set to run at startup. It always stayed where I put it, and I could customize which readings were shown. Fan Xpert ran from AI Suite, and could be adjusted without messing with the metering panel. Unfortunately, those software versions are incompatible with the Crosshair.
Crosshair V Formula-Z,FX-8350 Stock,4x8GiB Crucial Ballistix Sport DDR3-1600, 9-9-9-24,Gigabyte GTX 570, 861 MHz core,Asus GTX 580, 844 MHz core,Multiple WD HDDs: 2TB Black Hybrid,2TB Black,1TB Green,4TB RE4,2x-1TB Velociraptor,OCZ Z Series 1000w,Coolermaster Hyper 612 PWM, Fractal Design Define R4
System is a Photoshop/Lightroom workstation. Otherwise runs Great Internet Mersenne Prime Search 24/7. Prime 95 on CPU, mfaktc Trial Factoring on GPUs
