Digital Doc Fan Control

The digital doc can control up to 8 fans i think.... how does it control them? Do i have to get fans with variable speeds? or does it control it just by adjusting power?

It doesn't adjust the speed at which the fans moves.. It just turns them on/off at a whatever temperature you set it to.

Each fan is connected to the same # temp probe.

For example, if fan #1 is set to 40C, when temp probe #1 reaches 40C, fan #1 will go on.. when it falls to 39.9C, it will go off again.

The only problem with this setup is that the fans can sometimes go on/off repeatedly as the temp 'flickers' around the target temperature.. Kind of annoying actually.

You can actually add a relay switch to DD5 and it will automatically switches from 7V to 12V.
www.cooltechnica.com is giving the relay switch option when you purchase a DD5 from them.