Fiius
Hi seta,
 
You might be looking for a 4pin molex to a 3 pin fan adapter and they can be had for pretty cheap.  Just as an example, see http://www.frozencpu.com/cat/l3/g47/c251/s634/list/p1/Fan_Accessories-Fan_Cables-3_Pin_Adapters-Page1.html .  You may want to resize your fan wires to a custom length for cable management purposes, in which case you will need new pins and a crimp tool; http://www.frozencpu.com/products/1821/ele-173/3-Pin_Power_Supply_Connector_Pins_Set.html?tl=g51c393s2092 & http://www.frozencpu.com/products/3701/slt-16/FrozenCPU_Molex_Crimping_Tool.html?tl=g2c133s257 
 
This should help clean up the wiring.
 
~Fus

ty_ger07

seta8967
My plan was to have 3 360mm radiator, in push/pull setup. What would be the best way of routing these fans and cables? I thought using 3 splitters that have power from a SATA or MOLEX connector, I am trying to reduce the amount of cables and cable length so that why I use 3 splitters.. The top 2 splitters, 1 for each radiator setup, would feed their control cable into the 3rd front radiator splitters and this control cable into a single cpu header for PWM control. Then the SATA or MOLEX connector would provide power to the fans. Would this be possible? Are there splitters that add power via SATA or MOLEX? Is there anything I could do to simplify this and still reduce cabling?
 

Yes, exactly!  Remember that you need to be using 4-pin PWM fans for this to work properly though and that all splitters and adapters should also be designed for 4-pin PWM fans.
 
The SATA or Molex adapters provide power to the fans directly from the power supply and do not put any load on the fan header.  You can put an infinite number of fans on a single header using this method and never worry about damaging the header.
 
All the fans need power ("positive") and ground ("negative") from the SATA or Molex adapter.  Then, to control the fans, each fan needs a PWM signal to it from the fan header.  Finally, only ONE fan provides a tachometer feedback back to the header and acts as the master fan which all the other fans will mimic.
 
I am using this exact arrangement myself and I think it is simply a beautiful solution.  I never have to fiddle with a fan controller or remember to turn my fans up when weather or load changes or turn them down.  The fans change their speed automatically based on my motherboard's BIOS fan speed settings for the CPU fan header.  I use CPU temp to control my fan speed since the CPU is in my cooling loop and I find that it mitigates both CPU temp and GPU temp effectively in this configuration.  But, if you want to be even more exotic, you could connect your fans to a PWM output from one of your video cards and control your fan's speed based on GPU temperature.