The CPU FAN header is exactly what it says. A typical PC would have a single CPU and a heatsink mounted on top of it with a fan. That is where you would plug in the fan. Most gaming motherboards will allow you to control the speed of the heatsink fan that is connected to the CPU FAN header..
Keeping this in view, what is a fan header?
a fan header is the 3 or 4-pin socket on the mobo that supplies power to a fan. Some additionally can read the fan rpm (if signalled) & also have the voltage on them varied hence control fan speed. It is possible to power fans directly from the PSU or via a fan controller though so it isn't necessarily a drawback.
Also, can I plug a fan into CPU opt? A better option would be splitter cables for the normal case fan headers. Each header should support 3-4 fans without an issue. If you do use the CPU-OPT header I'd plug the rear ran into it since it's closest to the CPU and could work in tandem with the CPU fan this way.
Also question is, how many fans should a CPU header have?
Usually this means a maximum of two to possibly three fans per header.
Why do PC fans have 4 wires?
Add a fourth wire to control the fan's speed. The fan's speed is controlled by pulsing the voltage on the fourth wire. This wire does not power the fan. The pulsed signal changes the speed of the fan.
Related Question Answers
Is 1 fan enough for gaming PC?
I recommend at least 2 fans. One for intake and one for exhaust for best results. You can get by with just one fan though if you are careful. Fans are like $5-10 though so it really shouldn't be an issue.What does cha fan mean?
Asus refers to them as chassis fans or CHA-FAN. Regardless of what name you call it, these are the headers you use to plug in the fans that are used to cool your enclosure or case. As motherboards become more sophisticated, the headers on the motherboard take on more specialization.How many fans do you need for one header?
Using two parallel fans via splitter on a single motherboard fan header will draw twice as much amps as a single fan. If your fans are each 0.64A @ 12V, using two fans on a single motherboard fan header will draw 1.28A @ 12V, not 0.32A @ 12V.Can a 3 pin fan plug into 4 pin?
Electrically, there is no problem doing this - the fourth pin on the fan cable is used purely for PWM control and is not needed in order for the fan to run. So you can plug the 4-pin fan connector onto the 3-pin motherboard fan header, leaving the fourth pin not connected to anything.What is a fan header on a motherboard?
The motherboard you're getting has one CPU fan header and one case fan header. This means that you have enough fan headers to plug in your CPU fan and one other fans that are inside your case.Is it safe to use fan splitter?
You will be safe using a fan splitter as long as you the fans you are connecting does not draw more current than the motherboard header provides.Can I use a fan splitter on a fan splitter?
If you are referring to a two-way splitter plugged into another two-way splitter, then yes, it is possible. It just depends on the wattage of your headers and your fans.What is a system fan?
Alternatively referred to as a system fan, a case fan is located inside a computer, attached to the front or back of its case. Case fans help bring cool air into and blow hot air out of the case.How many fans can my PC have?
It is always our recommendation that you buy cases with a minimum of 3 fans (or at least slots for adding them yourself) for gaming systems, not counting the power supply, CPU, and GPU fans.What is a hybrid fan header?
Hybrid Fan Headers detect whether the cooling device uses PWM or Voltage mode and automatically switches settings accordingly. • Supports up to 2 amps with built-in overcurrent protection—a must for high-end high current fans.Can you connect two fans one header?
You could run every fan in your case (20 to be exact) on one header and be fine. When you run two fans on one header you are running them in parallel and that will double the resistance or Ohm load. This will cause twice the amount of amps to be pulled than normally would.What is a PWM fan?
PWM stands for pulse width modulation. PWM fans and/or pumps are found in some CPU coolers and GPU (aka graphics card) coolers. PWM works like a switch, turning on and off while controlling the level of power delivered to the fan or pump. PWM fans works in correlation with the motor, receiving full power or zero power.How many fans can you daisy chain?
Ehhhhh for most intents and purposes you can daisy chain as many fans as practically possible. In all honesty the upper limit would probably be around 30~50ish due to wire gauge, and added resistance due to a lot of connectors.Can 3 pin fans be controlled?
Actually, you MISunderstand that 4-pin fans only can be controlled. The speed of BOTH 3-pin and 4-pin fans can be controlled, but the method is different for the two types. For 3-pin fans, the connections to it are Ground to Pin #1, +VDC (varying) to Pin #2, and Speed signal on Pin #3.How many fans can I plug into my motherboard?
Case fans can be connected to the two chassis fan headers and the PSU fan too if you want to. Each header can split and power at least two or three modern fans. There is also a splitter cable that handles 5 fans and uses Molex power from the PSU.Are fan hubs safe?
Yes, Hubs are safe, and Silverstone is a reputable maker. The key characteristic of a HUB like that is that it gets all of the power for its fans directly from the PSU, and thus avoids the limit on amperage available at a mobo fan header. It still gets the control signals from the mobo, though.Can you plug a fan into a pump header?
If you plug in a case fan, it would just run at full speed (at first). If the header has PWM function, and you plugged in a PWM fan, then you can control its speed via current on constrant +12V DC.Where does the CPU fan plug in?
CPU cooling fans should ALWAYS be plugged into the header that is specifically labeled “CPU Fan” and not “CPU Optional” or any other header.Can you plug a fan into AIO pump?
Yes you can, there's not much difference in motors for AiO pump and any fan. 
