Please help me make a fan control decision with the NZXT Phantom 820. I'm running only four fans, the included front, top, rear and side. The MB is an Asus P9X79 WS which seems to have very good fan control. Would it be best to let the MB control fans or should I use the Phantom's digital fan controller? What are the pluses and minuses?

You are the best person to answer the question as you have the gear in front of you

Try em both. See what gives you the best noise/thermal result.

Some caveats: Asus mobos have PWM for the CPU fan. The rest look like PWM, but are really voltage controlled. Are the included fans PWM (4 pin) or voltage controlled (2 or 3 pin)?

The case fans are all three pin which I think doesn't provide optimal control with fan Asus xpert+.

I think Ill just experiment with both. I'm building the computer for a friend who is a gamer and he'll accept a bit of noise. I prefer inexpensive and silent builds.

If you don't mind running Asus AI Suite, then try the motherboard FanXpert first see how it works out, should be pretty simple, plug each fan to CHA_FAN headers, and the leave the CPU_FAN header for the cpu cooler fan.

If yo do mind running AI Suite, then go with the built fan controller.

The guy I'm building for likes to install every MB application but I just finished the HW build with case fans connected to the case fan controller so we'll try that first. After I do the software build we can switch to MB control.