OK.
First off, if one of your fans is rated for 2.8 Watts, you'll need a pot rated for at least 0.7 Watts. The closest one you'll find, I believe is 1 Watt.
If the same fan is rated 2.8W at 12V, then its (average) resistance is about 53 Ohms. A 100 Ohm pot would, at best, leave 4 volts for the fan, which is just below the minimum voltage, so that'll work.
In short: get 100 Ohm, 1 Watt, LINEAR pots.
If you need sources, I've got a few links.
|