Paperdoc January 4, 2018 9:24:09 AM
Normally one would connect ONLY the CPU cooling fan to the CPU_FAN header, and all the case fans to the only SYS_FAN header you have. That is because those two headers should be set to use different temperature sensors as their reference measurement. The CPU_FAN header will us the sensor inside the CPU chip, whereas the SYS_FAN header should be configured to use a sensor on the mobo.
In your case, OP, you have five case fans. You have said you already know the current draws and have calculated the loads for use with your two Splitters, but have not said how you assigned the fans to which headers. I'm guessing you have put at least one of the case fans on the CPU_FAN header (maybe two?) which is not exactly ideal, but it certainly CAN be done that way if the fan loads are OK. I'm also guessing that connecting all five case fans to the single SYS_FAN header would violate the load limits there. So probably you have arrived at your best option already.
Fully agree with CountMike: do NOT connect any fan to a PSU power connector.
Now, the fact you asked this question prompts me to ask for more info. How did you plan to do that? I'm guessing some of those case fans have two connectors on their wires - a smaller one with THREE holes and wires, and a larger one with four holes not only two wires attached to that. If that is the case, all those fans with smaller THREE-hole fan connectors are 3-pin fans that require you to use Voltage Control Mode from the relevant mobo fan header. That's the only way to control the speed of 3-pin fans. If you use PWM Mode on the header, those fans will always run full speed. So, is that the type of fan you have for the (five) case fans? I am guessing that the CPU cooling fan has FOUR wires from it to a connector with FOUR holes in it.