there is a strange rattle coming from my radiator, it is above the pump on the upper fan slot. (that doesn't seem to be a likely cause) this is the fan i have on it
Radiators do not have any moving parts to cause vibrations so it has the be something that moves. I would look at the fans and see if any of them are making any excessive vibrations. You might just have loose screws that need tightening or you could have a bad fan. The other possibility is something loose on the case right near the radiator that is making that rattling sound.
Having my PC making noise like that would drive me nuts lol.