When it wants to cool a computer Tower, we find ourselves quite quickly limited: If this isn't the tower which prevent you from adding more fans, it's your motherboard! Motherboards usually offer you the possibility to connect 2 minimum fans, with I would say an average of 4. Knowing that need you one for the cooling of your processor (unless you take a passive cooler), you "lose" automatically a place for fans of your chassis. One day, he even seemed to me that some power supplies require a connection to the motherboard for their fan. Unfortunately, I can no longer find the model or brand and maybe even that I smoked, but whatever it is, we find ourselves fast enough limited to connect the fans to the motherboard. Fortunately there are various solutions, and one of these solutions, it is a splitter (Splitter), the phobya radiator brand (which has a phobia?), the phobya radiator PWM 8 x 4 pine splitter. I thank Aquatuning France, specialist in cooling for computer, for having given me the chance to test this product. 
The phobya radiator PWM 8 x 4 pine splitter
So in practice, what can he do? It allows you to add up to 7 additional fans to the motherboard! And where generally the splitters don't allow to connect 3 pins fans, this one allows you to connect 8 fans 4 pines! The splitter consists of a surface, or you can connect 8 fans, and 1-wire to 3 Tips: one to connect to the motherboard as if it was a fan, one molex to provide electricity 8 fans, and one to the splitter. The splitter includes on its front a sticky portion in order to paste it in your lap and 2 sites dedicated to it. The 2 holes are separated by approximately 4 cm. The intention is good, but specifically, I'm not sure many housing have 2 holes open for this kind of screwing… For bonding, it'll still because at worst you can stick it on a wall (provided that your sons are long enough), but for screwing… 
To return to the function of splitteur, i.e. separating, I find more logical to speak of… multiplier or duplicator! What for? This is due to how it operates (and it's the only one, to the latest news, technology is such): the splitter is connected to the motherboard as a fan. You connect a maximum of 8 fans… but one of them (to a definite place) will give the speed to the motherboard and it will send the info (voltages, impulse) dedicated for this fan and only for this one! As a result, the info given to this fan are actually multiplied by 7: 7 for the other 7 fans. And no no splitter, car splitter means separate, divide. If it was actually a splitter, I would say other fans wouldn't turn or no, because the signal would be divided into 7! xD or you can say, multiplied and then divided xD why it is impossible for the motherboard to receive the data of 8 fans? Simply because the motherboard cannot take into account only one type of data: speed! A fan never turns at the same speed because it is controlled by the tension, however this tension varies constantly, share his nature! Because of this, if you give 2 different speeds to the motherboard, data will be corrupted because won't be able to tell the difference. The other fans "copy" a fan, one who will be placed as such, it is more preferable than to have 8 fans… identical! This may seem ridiculous, but often that is not all fans of the same brand and same model, because the tower is not specially all the same dedicated locations size, finance, availability, etc… and if more are connected the CPU cooler or cooling, it becomes almost inevitable there different fans! Same phobya radiator advises it in his mini-file, they advise in the channel 1 (so the fan which will be copied) the fan that has the highest value in starting voltage.
Conclusion
In short, a splitter which is what it was designed, inexpensive and space-saving. Not much to blame, missing just the 2 screws and the limit of the protections for 7 connectors that are in the open air… Link: in http://www.aquatuning.fr/refroidissement-air/ventilateurs-accessoires/17466/phobya-pwm-8x-4pin-splitter?c=2091 