I have a 902 and 5 tricools all hooked-up with 4pin molex to my psu.
PWR_FAN is usually a psu connection.
And CHA_FAN headers are for additional chassis/case fans.
There's no need to connect them to your mobo fan headers and the 3speed controls are on the exterior of your case.
Leave the exhaust fans at the factory setting which is low.
The front intakes can be adjusted to whatever you like i generally leave all 5 on low and occasionally i'll adjust my intakes higher when gaming heavily.
You mentioned that the 3 speed controls are on the case exterior, I guess you mean on your case? Mine doesn't seem to have that feature, it only has a power on and reset button. The case is an Antec Three Hundred.
I did a lot of googling about this matter and seems a lot of people are giving conflicting info and I'm still confused.
IF I can control the 2 additional fans - I was planning to put as intake - via my motherboard, I would definitely be interested rather than having to open up the case to adjust settings. My motherboard manual says it has chasis q-fan control.
Some people are claiming it's not possible with Tricools while others say you can set it to High, connect to the motherboard, and you can adjust easily.
I guess I will have to try it and find out, I just don't want to fry anything.
Where you get the TwoCool and TriCool fans determines on how you can control them. The fans that come with our cases can only be connected via molex. Out of the box, you wouldn't be able to control these aside from the hardware switches because they'd be plugged into the power supply, not the motherboard.
If you purchased one of our fans from a store, they do come with a 3-pin adapter that would allow you to plug the fan into the motherboard, allowing you further control.
Like Jessie said, tri cools have little black 3 way switches on a 3 inch ish cable that comes off the fan, so that when you plug them into the PSU you can adjust their speed, unless you mod the case you will need to open it up to adjust their speed but i find it unlikely that you will be adjusting their speed that often. Like Davcon said low is pretty good and quite quite on the Tricools so if you have 4 of them i would leave them set to that, it should keep everything nice and cool.