Extreme 7+ fan headers

That of course depends on the power usage/current ratings of the fans.

All fans are different, there are no standards for fan power usage.

In 120mm fans, power usage ranges from a maximum of under 0.1A (1.2W) for many Noctua fans, and the Nidec Servo "Gentle Typhoons" to well over 1.0A (12W+) for high speed Delta fans.

Using three fans on one fan header, hopefully the same model of fans, the combined total power usage must be under 1.0A (12W), so no more than 0.3A (3.6W) per fan. Of course the lower the power usage of the fans, the easier it will be on the board's fan headers.

If you want to monitor the speed of the fans, the three-way fan splitter you would use must only connect one of the fan's RPM wire to the board. Otherwise the multiple fan speed signals will result in a confused signal to the board.

FlesHBoX wrote: Thanks.  I'm using the Blacknoise Noiseblocker M12-1 fans, which according to the back of the box, pull .03 amps/.36 watts, which seems low at first glance, but the math works out. Am I correct in thinking that I would just need to remove the pin 3 (tachometer) wires for two of the fans in order to limit it to just one?

Yes, that is what I've done and it works. As you said, some splitters are sold with the tach wire on every connector on the thing! What is the point of that? Apparently there were even PWM splitters that were sold like that, which makes even less sense.

But I could swear that with some fans, even with the tach wire cut by me, that I would see odd speed readings sometimes. I may be dreaming!

Yes, your fans have a very low power usage, I checked the specs myself and you are right. 0.03A is very low power usage. You will have no problems with overloading the fan headers with those fans.