How many fans can be daisy chained into one header, for example cpu fan header? Can it cause black screen issue if 7 fans connected with pwm cable? Fans are cooler master halo 120. I am using cooler master controller that comes out of the box, it connected to psu, argb header on the mobo is not used.
If the motherboard fan header is connected to a powered fan hub, and the fans then get their power from the hub, the limit should be what the fan hub can handle, not the motherboard header. I'm not clear if you have both the fan motion and fan argb connected to a CM controller.
On the Crosshair VIII series (and most recent ASUS motherboards), the standard fan headers are 1A / 12W. So, any combination of fans which is adds up to less than that current / power limit. If your fans are getting power from the motherboard, that would be up to 3 (maybe 4) per header for the CM MF120. That fan has both a "rated current" and a "safety current", and I'm not exactly sure what CM are saying by that. Based on the rated current and "power consumption", you can have 4 per header for a total of 1A/12W. If they can actually draw the "safety current", then 3 per header (which would actually be 1.11A, but I feel that would be ok based on the other lower numbers being well under 1A).
Every fan is different. E.g. you can have up to 5 or 6 Noctua 120mm fans within the 1A limit, if memory serves.
The Coolermaster Masterfan MF120 Halo's rated current is .25a, you could put three fans on the cpu fan header and three fans on the cpu_opt header for a total of six fans (.75a for each header). The safety current is .37a and is the peak power draw, this could be when the fan first initially starts and with three fans could draw a maximum of 1.11a.
Since three fans could potentially draw 1.11a at startup, this could have a bearing on the longevity of the fan headers in the long run.
I'll agree with Murph, Coolermaster needs to specify what the safety current is.