The control board is straight forward.  Four three-pin connectors give you the ability to control the speed of up to four fans.  The unit is powered via a standard Molex plug seen to the left of the four power out connectors.

Installation and use

Installing the XTunner was no more difficult than screwing any other 5.25" device in place.  I want to reiterate the usefulness of the 7" Molex extender that really impresses its worth on you if you mount the device between or under a CD-ROM that traditionally makes reaching in to plug something in a royal pain.

Under power, the XTunner adjusts fan speed to any one of seven levels.  Of the six LED lights the first two are blue, the next two are green and the last two are red.  The blue is the low side of the speed spectrum while each push of the controller up button, inches up power until all six LEDs are lit indicating full power.  I said seven levels because the second slowest setting is the first blue LED lamp lit (the leftmost pic.)  The lowest setting is one more click of the '-' which makes this first LED blink.

Many mainboards have fan speed control written into the BIOS.  My personal preference is toward manual devices as the BIOS controlled type are will deafen you on POST with the fans running at full speed until the operating system is up and the fan speed is reined in.  This of course is not the case with the manual devices.

Using the BIOS PC Health screen we recorded the RPMs of each of the seven settings.  We selected a Thermaltake Smart Fan 2 as our test fan because of its wide variable speed range.  Our results are graphed below.  The three highest settings seem grouped a bit close but still very much acceptable.

One thing I thought odd was that I have used this exact fan with a Tt rheostat lead for some time and felt sure it could run lower (and quieter) than it did with the XTunner.  Disconnecting the XTunner and plugging in the Tt rheostat line, we measured the lowest and highest RPMs possible.

It was surprising to see that the lowest setting available with the XTunner was almost twice as high as the lowest for the Tt plug-in rheostat that came with the older Tt Smart Fan 2 units.  Through experience, I have found that an 80mm fan turning less than 2000 RPMs generally will keep a processor temperature much higher than you will be comfortable with.  More than once I have come running upon hearing a high temperature trip alarm go off when I had a fan set excessively low.  With this in mind, I can't fault Thermaltake for making the bottom end of the range being higher.  Remember that air flow will differ from fan to fan which reinforces my thoughts that Tt designed the low speed setting the way they did to be on the safe side.