Regarding CONTROL of the pump speed, we can get some info from the fact that the cable from it to the CPU_FAN header is a 3-pin type. The problem I saw is that we do not know exactly how the PUMP speed is being monitored, and whether that requires SmartFan to be Enabled.

But it is also possible that, just like the rad fan speeds, the Kraken system simply does its own pump speed measurement rather then get it from the mobo CPU_FAN header, and communicates that back to CAM via its USB data cable. SOME such systems actually get the PUMP speed from the mobo CPU_FAN header since you plug a cable from the pump into that mobo header specifically to sent the pump's speed there for failure monitoring. For sure the rad fan speeds it gets by a counter device built into the pump, which is where you plug in the rad fans. Now, CAM can tell you the Rad fan speeds AND the PUMP speed of its system. I expect this would be done whether or not SmartFan is Enabled, but I don't know. An important second function of the CPU_FAN header is to monitor the speed of its fan (in your case, of the Kraken PUMP) for FAILURE and generate a quick alarm and protective action. So if you turn SmartFan off, I am not sure whether the BIOS will do the fan speed reading job.

It also MAY be involved in actually counting the pulses in the fan speed signal lines to display fan speeds, although that function is not needed for fan control. SmartFan is the system built into the mobo BIOS (probably not a software utility loaded to run under Windows) that manipulates fan speeds to keep temperatures on target as measured at specific sensors. The Why? part mainly is my being cautious because the Kraken manual does NOT tell us exactly how it does some things, AND the mobo manual does not tell us all the things SmartFan does.

Bios aio pump control