All good mate, you'd be surprised how many people install AIO Liquid coolers incorrectly and then they complain about how noisy or poorly they perform

Hopefully you haven't done any permanent damage to the pump and that rattle goes away once you juice it up again.
The other common error is, not all AIO Liquid Coolers are designed with PWM fans and the Pump and the Fans are both supposed to run 100% (especially the older ones), yet people still connect them to PWM Headers or let Software alter their speed and so they do not run as fast as they should to get the results as advertised/tested/reviewed.
I'm running my H75 on an i7-4790K with a small OC to 4.6Mhz (turbo) - Pump on the CHA_FAN Header runs at 100% set manually in BIOS, I use Fan Expert 3 to manage all the PWM fans as well. system Idles at about 33degC with a room Ambient of about 25degC, gets up to about 54-57degC at load, 70-75degC on a stress test (which is why I keep my OC so small).
Just watch out though if you do use Fan Expert - it sets profiles for all the Fans in the case from Silent, Standard, Turbo and Extreme - on silent, it will shutdown the CPU Header if temp is below a certain level, same with the CHA_FAN headers - which means it'll turn off the pump and Radiator Fans if your not careful.